#はじめに
自分がSymfonyのメジャーバージョンアップ(2系から3系)対応の時につまづいた点をまとめた備忘録になります。
あくまでも自分の手順になるので間違った部分もあって込みの内容となってます。

#前提
・composer.jsonをバックアップにしておく。(一旦既存のcomposer.jsonは削除)
・composer.lockをベースに進める。
・Symfony3系で必要なディレクトリ構造にしておく。
app/consoleをbin/consoleに移動

mv app/console bin/console

・bin,var,testsフォルダ作成
app/cacheとapp/logsをvar/cacheとvar/logsにそれぞれ移動

mv app/cache var/cache

mv app/logs var/logs

#やりたいこと
Symfonyのバージョンを2.8から3.4にあげたい

#試したこと

###①コマンド

$ composer require symfony/symfony:3.4.*

###①エラー文

1/10:       https://packagist.jp/p/provider-latest$4cf7d7114d9080eaef2b098c9c6747426391b0733c821eadc7e5b2a6d8bba09a.json
    2/10:       https://packagist.jp/p/provider-2019$b58efe59a2edd8cb1f294321bfdd5ce6dceea464801de5091fe7f7b92b271ead.json
    3/10:       https://packagist.jp/p/provider-2019-04$846634f729841ed0ca87bfab924741b299429cf257f0c20862fc80ea825c8ef5.json
    4/10:       https://packagist.jp/p/provider-2019-07$c2d49956b25ba755169b4b9de37b67fd4abcc056f2f0cd77cf1a743337dcfdd4.json
    5/10:       https://packagist.jp/p/provider-2019-10$501573d09efc3a92295812c4e0fcb50ed491899e71af495de9e2d99e6c705343.json
    6/10:       https://packagist.jp/p/provider-2015$fcdc42bc9d9f73bc143a82a22dc0b63828d2d6b3bbee6eafedf565b3b1292dfe.json
    7/10:       https://packagist.jp/p/provider-2020-01$b8b7ba192459882e6f21064cf88e656ae2da0994b29d46d947460f7b9d4b61be.json
    8/10:       https://packagist.jp/p/provider-2016$70b1bfbaf9bbf0a2356191ccf9fa3da80f29f799e63ce19fbad6ddc331a6c901.json
    9/10:       https://packagist.jp/p/provider-2017$fbfa0d5bc998d7c9be7a4dc4259298ede80cbcbc6d535d506d952aec3d7f456c.json
    10/10:      https://packagist.jp/p/provider-2018$2616d7e41084b011a13edb000291f75cd6d5357ada473e6c6dcdb4eefb6aa6c7.json
    Finished: success: 10, skipped: 0, failure: 0, total: 10
Warning: You should avoid overwriting already defined auth settings for www.setasign.com.
./composer.json has been created
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - The requested package yahoojapan/yconnect-php-sdk could not be found in any version, there may be a typo in the package name.
  Problem 2
- fresh/doctrine-enum-bundle v2.6 requires symfony/symfony ~2.3 -> satisfiable by symfony/symfony[2.3.x-dev, 2.4.x-dev, 2.5.x-dev, 2.6.x-dev, 2.7.x-dev, 2.8.x-dev, v2.3.0, v2.3.0-BETA1, v2.3.0-BETA2, v2.3.0-RC1, v2.3.1, v2.3.10, v2.3.11, v2.3.12, v2.3.13, v2.3.14, v2.3.15, v2.3.16, v2.3.17, v2.3.18, v2.3.19, v2.3.2, v2.3.20, v2.3.21, v2.3.22, v2.3.23, v2.3.24, v2.3.25, v2.3.26, v2.3.27, v2.3.28, v2.3.29, v2.3.3, v2.3.30, v2.3.31, v2.3.32, v2.3.33, v2.3.34, v2.3.35, v2.3.36, v2.3.37, v2.3.38, v2.3.39, v2.3.4, v2.3.40, v2.3.41, v2.3.42, v2.3.5, v2.3.6, v2.3.7, v2.3.8, v2.3.9, v2.4.0, v2.4.0-BETA1, v2.4.0-BETA2, v2.4.0-RC1, v2.4.1, v2.4.10, v2.4.2, v2.4.3, v2.4.4, v2.4.5, v2.4.6, v2.4.7, v2.4.8, v2.4.9, v2.5.0, v2.5.0-BETA1, v2.5.0-BETA2, v2.5.0-RC1, v2.5.1, v2.5.10, v2.5.11, v2.5.12, v2.5.2, v2.5.3, v2.5.4, v2.5.5, v2.5.6, v2.5.7, v2.5.8, v2.5.9, v2.6.0, v2.6.0-BETA1, v2.6.0-BETA2, v2.6.1, v2.6.10, v2.6.11, v2.6.12, v2.6.13, v2.6.2, v2.6.3, v2.6.4, v2.6.5, v2.6.6, v2.6.7, v2.6.8, v2.6.9, v2.7.0, v2.7.0-BETA1, v2.7.0-BETA2, v2.7.1, v2.7.10, v2.7.11, v2.7.12, v2.7.13, v2.7.14, v2.7.15, v2.7.16, v2.7.17, v2.7.18, v2.7.19, v2.7.2, v2.7.20, v2.7.21, v2.7.22, v2.7.23, v2.7.24, v2.7.25, v2.7.26, v2.7.27, v2.7.28, v2.7.29, v2.7.3, v2.7.30, v2.7.31, v2.7.32, v2.7.33, v2.7.34, v2.7.35, v2.7.36, v2.7.37, v2.7.38, v2.7.39, v2.7.4, v2.7.40, v2.7.41, v2.7.42, v2.7.43, v2.7.44, v2.7.45, v2.7.46, v2.7.47, v2.7.48, v2.7.49, v2.7.5, v2.7.50, v2.7.51, v2.7.52, v2.7.6, v2.7.7, v2.7.8, v2.7.9, v2.8.0, v2.8.0-BETA1, v2.8.1, v2.8.10, v2.8.11, v2.8.12, v2.8.13, v2.8.14, v2.8.15, v2.8.16, v2.8.17, v2.8.18, v2.8.19, v2.8.2, v2.8.20, v2.8.21, v2.8.22, v2.8.23, v2.8.24, v2.8.25, v2.8.26, v2.8.27, v2.8.28, v2.8.29, v2.8.3, v2.8.30, v2.8.31, v2.8.32, v2.8.33, v2.8.34, v2.8.35, v2.8.36, v2.8.37, v2.8.38, v2.8.39, v2.8.4, v2.8.40, v2.8.41, v2.8.42, v2.8.43, v2.8.44, v2.8.45, v2.8.46, v2.8.47, v2.8.48, v2.8.49, v2.8.5, v2.8.50, v2.8.51, v2.8.52, v2.8.6, v2.8.7, v2.8.8, v2.8.9] but these conflict with your requirements or minimum-stability.
    - fresh/doctrine-enum-bundle v2.6 requires symfony/symfony ~2.3 -> satisfiable by symfony/symfony[2.3.x-dev, 2.4.x-dev, 2.5.x-dev, 2.6.x-dev, 2.7.x-dev, 2.8.x-dev, v2.3.0, v2.3.0-BETA1, v2.3.0-BETA2, v2.3.0-RC1, v2.3.1, v2.3.10, v2.3.11, v2.3.12, v2.3.13, v2.3.14, v2.3.15, v2.3.16, v2.3.17, v2.3.18, v2.3.19, v2.3.2, v2.3.20, v2.3.21, v2.3.22, v2.3.23, v2.3.24, v2.3.25, v2.3.26, v2.3.27, v2.3.28, v2.3.29, v2.3.3, v2.3.30, v2.3.31, v2.3.32, v2.3.33, v2.3.34, v2.3.35, v2.3.36, v2.3.37, v2.3.38, v2.3.39, v2.3.4, v2.3.40, v2.3.41, v2.3.42, v2.3.5, v2.3.6, v2.3.7, v2.3.8, v2.3.9, v2.4.0, v2.4.0-BETA1, v2.4.0-BETA2, v2.4.0-RC1, v2.4.1, v2.4.10, v2.4.2, v2.4.3, v2.4.4, v2.4.5, v2.4.6, v2.4.7, v2.4.8, v2.4.9, v2.5.0, v2.5.0-BETA1, v2.5.0-BETA2, v2.5.0-RC1, v2.5.1, v2.5.10, v2.5.11, v2.5.12, v2.5.2, v2.5.3, v2.5.4, v2.5.5, v2.5.6, v2.5.7, v2.5.8, v2.5.9, v2.6.0, v2.6.0-BETA1, v2.6.0-BETA2, v2.6.1, v2.6.10, v2.6.11, v2.6.12, v2.6.13, v2.6.2, v2.6.3, v2.6.4, v2.6.5, v2.6.6, v2.6.7, v2.6.8, v2.6.9, v2.7.0, v2.7.0-BETA1, v2.7.0-BETA2, v2.7.1, v2.7.10, v2.7.11, v2.7.12, v2.7.13, v2.7.14, v2.7.15, v2.7.16, v2.7.17, v2.7.18, v2.7.19, v2.7.2, v2.7.20, v2.7.21, v2.7.22, v2.7.23, v2.7.24, v2.7.25, v2.7.26, v2.7.27, v2.7.28, v2.7.29, v2.7.3, v2.7.30, v2.7.31, v2.7.32, v2.7.33, v2.7.34, v2.7.35, v2.7.36, v2.7.37, v2.7.38, v2.7.39, v2.7.4, v2.7.40, v2.7.41, v2.7.42, v2.7.43, v2.7.44, v2.7.45, v2.7.46, v2.7.47, v2.7.48, v2.7.49, v2.7.5, v2.7.50, v2.7.51, v2.7.52, v2.7.6, v2.7.7, v2.7.8, v2.7.9, v2.8.0, v2.8.0-BETA1, v2.8.1, v2.8.10, v2.8.11, v2.8.12, v2.8.13, v2.8.14, v2.8.15, v2.8.16, v2.8.17, v2.8.18, v2.8.19, v2.8.2, v2.8.20, v2.8.21, v2.8.22, v2.8.23, v2.8.24, v2.8.25, v2.8.26, v2.8.27, v2.8.28, v2.8.29, v2.8.3, v2.8.30, v2.8.31, v2.8.32, v2.8.33, v2.8.34, v2.8.35, v2.8.36, v2.8.37, v2.8.38, v2.8.39, v2.8.4, v2.8.40, v2.8.41, v2.8.42, v2.8.43, v2.8.44, v2.8.45, v2.8.46, v2.8.47, v2.8.48, v2.8.49, v2.8.5, v2.8.50, v2.8.51, v2.8.52, v2.8.6, v2.8.7, v2.8.8, v2.8.9] but these conflict with your requirements or minimum-stability.
    - Installation request for fresh/doctrine-enum-bundle (locked at v2.6) -> satisfiable by fresh/doctrine-enum-bundle[v2.6].

Potential causes:
 - A typo in the package name
 - The package is not available in a stable-enough version according to your minimum-stability setting
   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.
 - It's a private package and you forgot to add a custom repository to find it

Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.

Installation failed, deleting ./composer.json.

###①やったこと

composer.jsonを作成(空カッコのみ)

###②コマンド

$ composer clear-cache
$ composer install

###②エラー文

[RuntimeException]                                                                                                                                                                                                                                                    
  Failed to execute git clone --no-checkout '/home/webuser/.composer/cache/vcs/https---github.com-googleapis-google-api-php-client-services.git/' '/usr/local/***/***/***/vendor/google/apiclient-services' --dissociate --reference '/home/webuser/.composer/cac  
  he/vcs/https---github.com-googleapis-google-api-php-client-services.git/' && cd '/usr/local/***/***/***/vendor/google/apiclient-services' && git remote set-url origin 'https://github.com/googleapis/google-api-php-client-services.git.git' && git remote add  
   composer 'https://github.com/googleapis/google-api-php-client-services.git.git'                                                                                                                                                                                      
                                                                                                                                                                                                                                                                        
  Cloning into '/usr/local/***/***/***/vendor/google/apiclient-services'...                                                                                                                                                                                        
  done.                                                                                                                                                                                                                                                                 
  fatal: sha1 file '/usr/local/***/***/***/vendor/google/apiclient-services/.git/objects/pack/tmp_pack_oDVH9r' write error: No space left on device                                                                                                                
  fatal: cannot repack to clean up

###②やったこと
とりあえず以下を実践。
fatal: write error: No space left on device が出た場合は、不要ファイルを削除する

###③コマンド

$ composer clear-cache
$ composer install

変化無し

###④コマンド

$ composer require google/apiclient

###④エラー文

    1/13:       https://packagist.jp/p/provider-archived$95b7476cfaab2a59b34e1fbc07c1b5eaea0ffab22762f7f3baab102b0cc62822.json
    2/13:       https://packagist.jp/p/provider-latest$00705555cb11749e9f647332218bd6eea31f3c44ac0cf19c3ec8b2de93c39e94.json
    3/13:       https://packagist.jp/p/provider-2019$b58efe59a2edd8cb1f294321bfdd5ce6dceea464801de5091fe7f7b92b271ead.json
    4/13:       https://packagist.jp/p/provider-2015$fcdc42bc9d9f73bc143a82a22dc0b63828d2d6b3bbee6eafedf565b3b1292dfe.json
    5/13:       https://packagist.jp/p/provider-2019-07$80c13ad4fc7b9244c01282b7017b83258aa586cf2159d5dc40554548b0d74f06.json
    6/13:       https://packagist.jp/p/provider-2019-04$f741ea81917e0209aed1d18f1ffb248e3b6b320c6e448095017710276650c3d9.json
    7/13:       https://packagist.jp/p/provider-2013$a4281ae322607a7439284d74fbbdbf0cb8f3759c67a28da4efaca8d3d503316e.json
    8/13:       https://packagist.jp/p/provider-2014$be74d9d45182ab129f4f83b1b6e51221aade5e77aa94291ebd3a2f7cc590d533.json
    9/13:       https://packagist.jp/p/provider-2019-10$de62c9f6b36b970ee02c3ee361eb6c8f040a7f577d1c8ebe402f0f45b587a739.json
    10/13:      https://packagist.jp/p/provider-2016$70b1bfbaf9bbf0a2356191ccf9fa3da80f29f799e63ce19fbad6ddc331a6c901.json
    11/13:      https://packagist.jp/p/provider-2020-01$61c6414b0fed3212509037ace96b8b443274d7c0ab57d072fd96eecb63c63872.json
    12/13:      https://packagist.jp/p/provider-2017$fbfa0d5bc998d7c9be7a4dc4259298ede80cbcbc6d535d506d952aec3d7f456c.json
    13/13:      https://packagist.jp/p/provider-2018$8b4641ea629199247c3b2ac26414ff672de01bca6d3451908001e7e6ae255a3a.json
    Finished: success: 13, skipped: 0, failure: 0, total: 13
Using version ^2.4 for google/apiclient
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$security-core.json into cache failed after 409600 of 2741220 bytes written, only 17190912 bytes of free space available
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Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$http-kernel.json into cache failed after 319488 of 2545282 bytes written, only 17100800 bytes of free space available
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Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$security-csrf.json into cache failed after 319488 of 2580940 bytes written, only 17100800 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$stopwatch.json into cache failed after 319488 of 2023685 bytes written, only 17100800 bytes of free space available
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Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$security.json into cache failed after 184320 of 2492292 bytes written, only 16965632 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$security-guard.json into cache failed after 184320 of 1873112 bytes written, only 16965632 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$security-http.json into cache failed after 184320 of 2732471 bytes written, only 16965632 bytes of free space available
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Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-willdurand$negotiation.json into cache failed after 28672 of 45146 bytes written, only 16809984 bytes of free space available
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Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-knplabs$knp-components.json into cache failed after 0 of 53638 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-knplabs$knp-gaufrette-bundle.json into cache failed after 0 of 18797 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-knplabs$knp-markdown-bundle.json into cache failed after 0 of 26594 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-michelf$php-markdown.json into cache failed after 0 of 29381 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-knplabs$knp-paginator-bundle.json into cache failed after 0 of 37091 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-kriswallsmith$assetic.json into cache failed after 0 of 85569 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$process.json into cache failed after 0 of 2147642 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-ruler$ruler.json into cache failed after 0 of 3450 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-sensio$distribution-bundle.json into cache failed after 0 of 168593 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-sensiolabs$security-checker.json into cache failed after 0 of 43360 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$http-client.json into cache failed after 0 of 237680 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$http-client-contracts.json into cache failed after 0 of 28965 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-sensio$framework-extra-bundle.json into cache failed after 0 of 135681 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-setasign$fpdi.json into cache failed after 0 of 37202 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-setasign$fpdi-tcpdf.json into cache failed after 0 of 11660 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-tecnickcom$tcpdf.json into cache failed after 0 of 162381 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-swiftmailer$swiftmailer.json into cache failed after 0 of 68536 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$assetic-bundle.json into cache failed after 0 of 49856 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$monolog-bundle.json into cache failed after 0 of 124079 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$monolog-bridge.json into cache failed after 0 of 2372971 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$swiftmailer-bundle.json into cache failed after 0 of 157828 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-vich$uploader-bundle.json into cache failed after 0 of 135836 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-doctrine$data-fixtures.json into cache failed after 0 of 36781 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-doctrine$doctrine-fixtures-bundle.json into cache failed after 0 of 35147 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-sensio$generator-bundle.json into cache failed after 0 of 82711 bytes written, only 16781312 bytes of free space available
Writing /home/webuser/.composer/cache/repo/https---packagist.jp/provider-symfony$phpunit-bridge.json into cache failed after 0 of 365725 bytes written, only 16781312 bytes of free space available
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - The requested package yahoojapan/yconnect-php-sdk could not be found in any version, there may be a typo in the package name.

Potential causes:
 - A typo in the package name
 - The package is not available in a stable-enough version according to your minimum-stability setting
   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.
 - It's a private package and you forgot to add a custom repository to find it

Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.

Installation failed, reverting ./composer.json to its original content.

###④やったこと

composer の「secure-http false」(global 対応)

composer config —global secure-http false

###⑤コマンド

$ composer clear-cache
$ composer install

###⑤エラー文

Package operations: 40 installs, 0 updates, 0 removals
  - Installing google/apiclient-services (v0.123): Loading from cache
    Failed to execute (50) unzip -qq  '/usr/local/***/***/***/vendor/google/apiclient-services/2c2768d65ea1f6e490e1e5790691a2f5' -d '/usr/local/***/***/***/vendor/composer/ef5e46f2'

/usr/local/***/***/***/vendor/composer/ef5e46f2/googleapis-google-api-php-client-services-a8c3c75/src/Google/Service/CloudSearch/Filter.php:  write error (disk full?).  Continue? (y/n/^C) 
warning:  /usr/local/***/***/***/vendor/composer/ef5e46f2/googleapis-google-api-php-client-services-a8c3c75/src/Google/Service/CloudSearch/Filter.php is probably truncated

    The archive may contain identical file names with different capitalization (which fails on case insensitive filesystems)
    Unzip with unzip command failed, falling back to ZipArchive class
    Failed to download google/apiclient-services from dist: The archive may contain identical file names with different capitalization (which fails on case insensitive filesystems): ZipArchive::extractTo(): No space left on device
    Now trying to download from source
  - Installing google/apiclient-services (v0.123): Cloning a8c3c75637 from cache

                                                                                                                                                                                                                                                                        
  [RuntimeException]                                                                                                                                                                                                                                                    
  Failed to execute git clone --no-checkout '/home/webuser/.composer/cache/vcs/https---github.com-googleapis-google-api-php-client-services.git/' '/usr/local/***/***/***/vendor/google/apiclient-services' --dissociate --reference '/home/webuser/.composer/cac  
  he/vcs/https---github.com-googleapis-google-api-php-client-services.git/' && cd '/usr/local/***/***/***/vendor/google/apiclient-services' && git remote set-url origin 'https://github.com/googleapis/google-api-php-client-services.git.git' && git remote add  
   composer 'https://github.com/googleapis/google-api-php-client-services.git.git'                                                                                                                                                                                      
                                                                                                                                                                                                                                                                        
  Cloning into '/usr/local/***/***/***/vendor/google/apiclient-services'...                                                                                                                                                                                        
  done.                                                                                                                                                                                                                                                                 
  fatal: sha1 file '/usr/local/***/***/***/vendor/google/apiclient-services/.git/objects/pack/tmp_pack_WD3HX6' write error: No space left on device                                                                                                                
  fatal: cannot repack to clean up

###⑤やったこと

No space left on device とエラーが出るときの対処法

$ sudo find . -xdev -type f | cut -d "/" -f 2 | sort | uniq -c | sort -n

vendorをバックアップで所持してたのでそれを削除

###⑥コマンド

$ composer clear-cache
$ composer install

###⑥エラー文

1/13:       https://packagist.jp/p/provider-archived$95b7476cfaab2a59b34e1fbc07c1b5eaea0ffab22762f7f3baab102b0cc62822.json
    2/13:       https://packagist.jp/p/provider-latest$a69ccff12176ee43cdb2d6e01240040639a850d1b678ef3ec7d2c673598b0c6e.json
    3/13:       https://packagist.jp/p/provider-2019-07$3ddfc01c04c27d241c897384ae2847efeb910ac8a5abc20c9ac11cd6f6c65c72.json
    4/13:       https://packagist.jp/p/provider-2014$be74d9d45182ab129f4f83b1b6e51221aade5e77aa94291ebd3a2f7cc590d533.json
    5/13:       https://packagist.jp/p/provider-2019-04$d45a3e66503558e1fbda0dde8beac09af23ff26a574113b0e85619e2b4641374.json
    6/13:       https://packagist.jp/p/provider-2013$a4281ae322607a7439284d74fbbdbf0cb8f3759c67a28da4efaca8d3d503316e.json
    7/13:       https://packagist.jp/p/provider-2019-10$5d553a04fa27e0799d7fa35ae1103a50dd506e26366d379144d5f7873d9ec4e4.json
    8/13:       https://packagist.jp/p/provider-2020-01$85f71ee5ff352526009d397474a8d4fecb22d1d03f5de9ea590f8f76c04d8067.json
    9/13:       https://packagist.jp/p/provider-2019$b58efe59a2edd8cb1f294321bfdd5ce6dceea464801de5091fe7f7b92b271ead.json
    10/13:      https://packagist.jp/p/provider-2017$fbfa0d5bc998d7c9be7a4dc4259298ede80cbcbc6d535d506d952aec3d7f456c.json
    11/13:      https://packagist.jp/p/provider-2015$fcdc42bc9d9f73bc143a82a22dc0b63828d2d6b3bbee6eafedf565b3b1292dfe.json
    12/13:      https://packagist.jp/p/provider-2018$8b4641ea629199247c3b2ac26414ff672de01bca6d3451908001e7e6ae255a3a.json
    13/13:      https://packagist.jp/p/provider-2016$70b1bfbaf9bbf0a2356191ccf9fa3da80f29f799e63ce19fbad6ddc331a6c901.json
    Finished: success: 13, skipped: 0, failure: 0, total: 13
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - fresh/doctrine-enum-bundle v2.6 requires symfony/symfony ~2.3 -> satisfiable by symfony/symfony[2.3.x-dev, 2.4.x-dev, 2.5.x-dev, 2.6.x-dev, 2.7.x-dev, 2.8.x-dev, v2.3.0, v2.3.0-BETA1, v2.3.0-BETA2, v2.3.0-RC1, v2.3.1, v2.3.10, v2.3.11, v2.3.12, v2.3.13, v2.3.14, v2.3.15, v2.3.16, v2.3.17, v2.3.18, v2.3.19, v2.3.2, v2.3.20, v2.3.21, v2.3.22, v2.3.23, v2.3.24, v2.3.25, v2.3.26, v2.3.27, v2.3.28, v2.3.29, v2.3.3, v2.3.30, v2.3.31, v2.3.32, v2.3.33, v2.3.34, v2.3.35, v2.3.36, v2.3.37, v2.3.38, v2.3.39, v2.3.4, v2.3.40, v2.3.41, v2.3.42, v2.3.5, v2.3.6, v2.3.7, v2.3.8, v2.3.9, v2.4.0, v2.4.0-BETA1, v2.4.0-BETA2, v2.4.0-RC1, v2.4.1, v2.4.10, v2.4.2, v2.4.3, v2.4.4, v2.4.5, v2.4.6, v2.4.7, v2.4.8, v2.4.9, v2.5.0, v2.5.0-BETA1, v2.5.0-BETA2, v2.5.0-RC1, v2.5.1, v2.5.10, v2.5.11, v2.5.12, v2.5.2, v2.5.3, v2.5.4, v2.5.5, v2.5.6, v2.5.7, v2.5.8, v2.5.9, v2.6.0, v2.6.0-BETA1, v2.6.0-BETA2, v2.6.1, v2.6.10, v2.6.11, v2.6.12, v2.6.13, v2.6.2, v2.6.3, v2.6.4, v2.6.5, v2.6.6, v2.6.7, v2.6.8, v2.6.9, v2.7.0, v2.7.0-BETA1, v2.7.0-BETA2, v2.7.1, v2.7.10, v2.7.11, v2.7.12, v2.7.13, v2.7.14, v2.7.15, v2.7.16, v2.7.17, v2.7.18, v2.7.19, v2.7.2, v2.7.20, v2.7.21, v2.7.22, v2.7.23, v2.7.24, v2.7.25, v2.7.26, v2.7.27, v2.7.28, v2.7.29, v2.7.3, v2.7.30, v2.7.31, v2.7.32, v2.7.33, v2.7.34, v2.7.35, v2.7.36, v2.7.37, v2.7.38, v2.7.39, v2.7.4, v2.7.40, v2.7.41, v2.7.42, v2.7.43, v2.7.44, v2.7.45, v2.7.46, v2.7.47, v2.7.48, v2.7.49, v2.7.5, v2.7.50, v2.7.51, v2.7.52, v2.7.6, v2.7.7, v2.7.8, v2.7.9, v2.8.0, v2.8.0-BETA1, v2.8.1, v2.8.10, v2.8.11, v2.8.12, v2.8.13, v2.8.14, v2.8.15, v2.8.16, v2.8.17, v2.8.18, v2.8.19, v2.8.2, v2.8.20, v2.8.21, v2.8.22, v2.8.23, v2.8.24, v2.8.25, v2.8.26, v2.8.27, v2.8.28, v2.8.29, v2.8.3, v2.8.30, v2.8.31, v2.8.32, v2.8.33, v2.8.34, v2.8.35, v2.8.36, v2.8.37, v2.8.38, v2.8.39, v2.8.4, v2.8.40, v2.8.41, v2.8.42, v2.8.43, v2.8.44, v2.8.45, v2.8.46, v2.8.47, v2.8.48, v2.8.49, v2.8.5, v2.8.50, v2.8.51, v2.8.52, v2.8.6, v2.8.7, v2.8.8, v2.8.9] but these conflict with your requirements or minimum-stability.
    - fresh/doctrine-enum-bundle v2.6 requires symfony/symfony ~2.3 -> satisfiable by symfony/symfony[2.3.x-dev, 2.4.x-dev, 2.5.x-dev, 2.6.x-dev, 2.7.x-dev, 2.8.x-dev, v2.3.0, v2.3.0-BETA1, v2.3.0-BETA2, v2.3.0-RC1, v2.3.1, v2.3.10, v2.3.11, v2.3.12, v2.3.13, v2.3.14, v2.3.15, v2.3.16, v2.3.17, v2.3.18, v2.3.19, v2.3.2, v2.3.20, v2.3.21, v2.3.22, v2.3.23, v2.3.24, v2.3.25, v2.3.26, v2.3.27, v2.3.28, v2.3.29, v2.3.3, v2.3.30, v2.3.31, v2.3.32, v2.3.33, v2.3.34, v2.3.35, v2.3.36, v2.3.37, v2.3.38, v2.3.39, v2.3.4, v2.3.40, v2.3.41, v2.3.42, v2.3.5, v2.3.6, v2.3.7, v2.3.8, v2.3.9, v2.4.0, v2.4.0-BETA1, v2.4.0-BETA2, v2.4.0-RC1, v2.4.1, v2.4.10, v2.4.2, v2.4.3, v2.4.4, v2.4.5, v2.4.6, v2.4.7, v2.4.8, v2.4.9, v2.5.0, v2.5.0-BETA1, v2.5.0-BETA2, v2.5.0-RC1, v2.5.1, v2.5.10, v2.5.11, v2.5.12, v2.5.2, v2.5.3, v2.5.4, v2.5.5, v2.5.6, v2.5.7, v2.5.8, v2.5.9, v2.6.0, v2.6.0-BETA1, v2.6.0-BETA2, v2.6.1, v2.6.10, v2.6.11, v2.6.12, v2.6.13, v2.6.2, v2.6.3, v2.6.4, v2.6.5, v2.6.6, v2.6.7, v2.6.8, v2.6.9, v2.7.0, v2.7.0-BETA1, v2.7.0-BETA2, v2.7.1, v2.7.10, v2.7.11, v2.7.12, v2.7.13, v2.7.14, v2.7.15, v2.7.16, v2.7.17, v2.7.18, v2.7.19, v2.7.2, v2.7.20, v2.7.21, v2.7.22, v2.7.23, v2.7.24, v2.7.25, v2.7.26, v2.7.27, v2.7.28, v2.7.29, v2.7.3, v2.7.30, v2.7.31, v2.7.32, v2.7.33, v2.7.34, v2.7.35, v2.7.36, v2.7.37, v2.7.38, v2.7.39, v2.7.4, v2.7.40, v2.7.41, v2.7.42, v2.7.43, v2.7.44, v2.7.45, v2.7.46, v2.7.47, v2.7.48, v2.7.49, v2.7.5, v2.7.50, v2.7.51, v2.7.52, v2.7.6, v2.7.7, v2.7.8, v2.7.9, v2.8.0, v2.8.0-BETA1, v2.8.1, v2.8.10, v2.8.11, v2.8.12, v2.8.13, v2.8.14, v2.8.15, v2.8.16, v2.8.17, v2.8.18, v2.8.19, v2.8.2, v2.8.20, v2.8.21, v2.8.22, v2.8.23, v2.8.24, v2.8.25, v2.8.26, v2.8.27, v2.8.28, v2.8.29, v2.8.3, v2.8.30, v2.8.31, v2.8.32, v2.8.33, v2.8.34, v2.8.35, v2.8.36, v2.8.37, v2.8.38, v2.8.39, v2.8.4, v2.8.40, v2.8.41, v2.8.42, v2.8.43, v2.8.44, v2.8.45, v2.8.46, v2.8.47, v2.8.48, v2.8.49, v2.8.5, v2.8.50, v2.8.51, v2.8.52, v2.8.6, v2.8.7, v2.8.8, v2.8.9] but these conflict with your requirements or minimum-stability.
    - fresh/doctrine-enum-bundle v2.6 requires symfony/symfony ~2.3 -> satisfiable by symfony/symfony[2.3.x-dev, 2.4.x-dev, 2.5.x-dev, 2.6.x-dev, 2.7.x-dev, 2.8.x-dev, v2.3.0, v2.3.0-BETA1, v2.3.0-BETA2, v2.3.0-RC1, v2.3.1, v2.3.10, v2.3.11, v2.3.12, v2.3.13, v2.3.14, v2.3.15, v2.3.16, v2.3.17, v2.3.18, v2.3.19, v2.3.2, v2.3.20, v2.3.21, v2.3.22, v2.3.23, v2.3.24, v2.3.25, v2.3.26, v2.3.27, v2.3.28, v2.3.29, v2.3.3, v2.3.30, v2.3.31, v2.3.32, v2.3.33, v2.3.34, v2.3.35, v2.3.36, v2.3.37, v2.3.38, v2.3.39, v2.3.4, v2.3.40, v2.3.41, v2.3.42, v2.3.5, v2.3.6, v2.3.7, v2.3.8, v2.3.9, v2.4.0, v2.4.0-BETA1, v2.4.0-BETA2, v2.4.0-RC1, v2.4.1, v2.4.10, v2.4.2, v2.4.3, v2.4.4, v2.4.5, v2.4.6, v2.4.7, v2.4.8, v2.4.9, v2.5.0, v2.5.0-BETA1, v2.5.0-BETA2, v2.5.0-RC1, v2.5.1, v2.5.10, v2.5.11, v2.5.12, v2.5.2, v2.5.3, v2.5.4, v2.5.5, v2.5.6, v2.5.7, v2.5.8, v2.5.9, v2.6.0, v2.6.0-BETA1, v2.6.0-BETA2, v2.6.1, v2.6.10, v2.6.11, v2.6.12, v2.6.13, v2.6.2, v2.6.3, v2.6.4, v2.6.5, v2.6.6, v2.6.7, v2.6.8, v2.6.9, v2.7.0, v2.7.0-BETA1, v2.7.0-BETA2, v2.7.1, v2.7.10, v2.7.11, v2.7.12, v2.7.13, v2.7.14, v2.7.15, v2.7.16, v2.7.17, v2.7.18, v2.7.19, v2.7.2, v2.7.20, v2.7.21, v2.7.22, v2.7.23, v2.7.24, v2.7.25, v2.7.26, v2.7.27, v2.7.28, v2.7.29, v2.7.3, v2.7.30, v2.7.31, v2.7.32, v2.7.33, v2.7.34, v2.7.35, v2.7.36, v2.7.37, v2.7.38, v2.7.39, v2.7.4, v2.7.40, v2.7.41, v2.7.42, v2.7.43, v2.7.44, v2.7.45, v2.7.46, v2.7.47, v2.7.48, v2.7.49, v2.7.5, v2.7.50, v2.7.51, v2.7.52, v2.7.6, v2.7.7, v2.7.8, v2.7.9, v2.8.0, v2.8.0-BETA1, v2.8.1, v2.8.10, v2.8.11, v2.8.12, v2.8.13, v2.8.14, v2.8.15, v2.8.16, v2.8.17, v2.8.18, v2.8.19, v2.8.2, v2.8.20, v2.8.21, v2.8.22, v2.8.23, v2.8.24, v2.8.25, v2.8.26, v2.8.27, v2.8.28, v2.8.29, v2.8.3, v2.8.30, v2.8.31, v2.8.32, v2.8.33, v2.8.34, v2.8.35, v2.8.36, v2.8.37, v2.8.38, v2.8.39, v2.8.4, v2.8.40, v2.8.41, v2.8.42, v2.8.43, v2.8.44, v2.8.45, v2.8.46, v2.8.47, v2.8.48, v2.8.49, v2.8.5, v2.8.50, v2.8.51, v2.8.52, v2.8.6, v2.8.7, v2.8.8, v2.8.9] but these conflict with your requirements or minimum-stability.
    - Installation request for fresh/doctrine-enum-bundle (locked at v2.6) -> satisfiable by fresh/doctrine-enum-bundle[v2.6].


Installation failed, reverting ./composer.json to its original content.

###⑥やったこと
無問題 Composer でパッケージの削除は composer remove で問題ない

$ composer clear-cache
$ composer remove fresh/doctrine-enum-bundle

fresh/doctrine-enum-bundle is not required in your composer.json and has not been removed
Loading composer repositories with package information
Updating dependencies (including require-dev)
    1/10:       https://codeload.github.com/symfony/polyfill-intl-icu/legacy.zip/727b3bb5bfa7ca9eeb86416784cf1c08a6289b86
    2/10:       https://codeload.github.com/symfony/polyfill-apcu/legacy.zip/f5a6efd9d9f68790120734f80f8fda972981edab
    3/10:       https://codeload.github.com/symfony/polyfill-php56/legacy.zip/16ec91cb06998b609501b55b7177b7d7c02badb3
    4/10:       https://codeload.github.com/symfony/polyfill-php55/legacy.zip/58a98ed90b40a15a1a76c59417386395d5b1ec76
    5/10:       https://codeload.github.com/symfony/polyfill-php54/legacy.zip/a8076ba7fd176d773d0e4aadb5b3cc7680a1c0a6
    6/10:       https://codeload.github.com/symfony/polyfill-ctype/legacy.zip/fbdeaec0df06cf3d51c93de80c7eb76e271f5a38
    7/10:       https://codeload.github.com/symfony/polyfill-mbstring/legacy.zip/34094cfa9abe1f0f14f48f490772db7a775559f2
    8/10:       https://codeload.github.com/symfony/polyfill-php70/legacy.zip/419c4940024c30ccc033650373a1fe13890d3255
    9/10:       https://codeload.github.com/symfony/polyfill-util/legacy.zip/ba3cfcea6d0192cae46c62041f61cbb704b526d3
    10/10:      https://codeload.github.com/twigphp/Twig/legacy.zip/87b2ea9d8f6fd014d0621ca089bb1b3769ea3f8e
    Finished: success: 10, skipped: 0, failure: 0, total: 10
Package operations: 0 installs, 10 updates, 3 removals
  - Removing fresh/doctrine-enum-bundle (v2.6)
  - Removing doctrine/orm (v2.5.14)
  - Removing yahoojapan/yconnect-php-sdk (dev-master)
  - Updating symfony/polyfill-mbstring (v1.13.1 => v1.14.0): Loading from cache
  - Updating symfony/polyfill-apcu (v1.13.1 => v1.14.0): Loading from cache
  - Updating symfony/polyfill-ctype (v1.13.1 => v1.14.0): Loading from cache
  - Updating twig/twig (v1.42.4 => v1.42.5): Loading from cache
  - Updating symfony/polyfill-util (v1.13.1 => v1.14.0):  Checking out ba3cfcea6d
  - Updating symfony/polyfill-php70 (v1.13.1 => v1.14.0):  Checking out 419c494002
  - Updating symfony/polyfill-php56 (v1.13.1 => v1.14.0):  Checking out 16ec91cb06
  - Updating symfony/polyfill-php55 (v1.13.1 => v1.14.0): Loading from cache
  - Updating symfony/polyfill-php54 (v1.13.1 => v1.14.0): Loading from cache
  - Updating symfony/polyfill-intl-icu (v1.13.1 => v1.14.0): Loading from cache
Package sensio/generator-bundle is abandoned, you should avoid using it. Use symfony/maker-bundle instead.
Package setasign/fpdi-tcpdf is abandoned, you should avoid using it. No replacement was suggested.
Package symfony/assetic-bundle is abandoned, you should avoid using it. Use symfony/webpack-encore-pack instead.
Writing lock file
Generating autoload files

###⑦コマンド

$ composer clear-cache
$ composer require symfony/symfony:3.4.*

1/13:       https://packagist.jp/p/provider-archived$95b7476cfaab2a59b34e1fbc07c1b5eaea0ffab22762f7f3baab102b0cc62822.json
    2/13:       https://packagist.jp/p/provider-2019-04$d45a3e66503558e1fbda0dde8beac09af23ff26a574113b0e85619e2b4641374.json
    3/13:       https://packagist.jp/p/provider-2015$fcdc42bc9d9f73bc143a82a22dc0b63828d2d6b3bbee6eafedf565b3b1292dfe.json
    4/13:       https://packagist.jp/p/provider-latest$eb506ff0de275e8ffb00d4fe29d4aa5995ba03064fb119754d217c71e3d31369.json
    5/13:       https://packagist.jp/p/provider-2014$be74d9d45182ab129f4f83b1b6e51221aade5e77aa94291ebd3a2f7cc590d533.json
    6/13:       https://packagist.jp/p/provider-2013$a4281ae322607a7439284d74fbbdbf0cb8f3759c67a28da4efaca8d3d503316e.json
    7/13:       https://packagist.jp/p/provider-2019$ca736e92043d8b9c244e1a685fe9a57d34068aa817ac3e8a8580d213eac55a6d.json
    8/13:       https://packagist.jp/p/provider-2016$70b1bfbaf9bbf0a2356191ccf9fa3da80f29f799e63ce19fbad6ddc331a6c901.json
    9/13:       https://packagist.jp/p/provider-2019-07$3ddfc01c04c27d241c897384ae2847efeb910ac8a5abc20c9ac11cd6f6c65c72.json
    10/13:      https://packagist.jp/p/provider-2019-10$0c14d243fcc3fe5eefd3d5871f06933e6508f7b3eb22d14104af2c1f462f4e75.json
    11/13:      https://packagist.jp/p/provider-2020-01$577034082b2d01ebf8e76ad9a6765ab1803722d14741b1a4776bf9a85634d847.json
    12/13:      https://packagist.jp/p/provider-2017$fbfa0d5bc998d7c9be7a4dc4259298ede80cbcbc6d535d506d952aec3d7f456c.json
    13/13:      https://packagist.jp/p/provider-2018$8b4641ea629199247c3b2ac26414ff672de01bca6d3451908001e7e6ae255a3a.json
    Finished: success: 13, skipped: 0, failure: 0, total: 13
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
    1/5:        https://codeload.github.com/php-fig/container/legacy.zip/b7ce3b176482dbbc1245ebf52b181af44c2cf55f
    2/5:        https://codeload.github.com/php-fig/link/legacy.zip/eea8e8662d5cd3ae4517c9b864493f59fca95562
    3/5:        https://codeload.github.com/php-fig/simple-cache/legacy.zip/408d5eafb83c57f6365a3ca330ff23aa4a5fa39b
    4/5:        https://codeload.github.com/php-fig/link-util/legacy.zip/47f55860678a9e202206047bc02767556d298106
    5/5:        https://codeload.github.com/symfony/symfony/legacy.zip/c5a882db43e7163114edffdf3ee2f988328fa6c4
    Finished: success: 5, skipped: 0, failure: 0, total: 5
Package operations: 4 installs, 1 update, 0 removals
  - Updating symfony/symfony (v2.8.52 => v3.4.38): Loading from cache    Failed to execute (50) unzip -qq  '/usr/local/***/***/***/vendor/symfony/symfony/230a17ab582b510f92904d5041cd1188' -d '/usr/local/***/***/***/vendor/composer/62bf0239'

/usr/local/***/***/***/vendor/composer/62bf0239/symfony-symfony-c5a882d/src/Symfony/Component/Process/Pipes/PipesInterface.php:  write error (disk full?).  Continue? (y/n/^C) 
warning:  /usr/local/***/***/***/vendor/composer/62bf0239/symfony-symfony-c5a882d/src/Symfony/Component/Process/Pipes/PipesInterface.php is probably truncated

    The archive may contain identical file names with different capitalization (which fails on case insensitive filesystems)
    Unzip with unzip command failed, falling back to ZipArchive class

  - Installing psr/simple-cache (1.0.1): Loading from cache
  - Installing psr/link (1.0.0): Loading from cache
  - Installing psr/container (1.0.0): Loading from cache
  - Installing fig/link-util (1.1.0): Loading from cache
Package sensio/generator-bundle is abandoned, you should avoid using it. Use symfony/maker-bundle instead.
Package setasign/fpdi-tcpdf is abandoned, you should avoid using it. No replacement was suggested.
Package symfony/assetic-bundle is abandoned, you should avoid using it. Use symfony/webpack-encore-pack instead.
Writing lock file
Generating autoload files
1 package you are using is looking for funding.
Use the composer fund command to find out more!

これでSymfonyのバージョンは3.4に上がりました！

#最後に
結構沼った部分もあって不要な手順もきっとありますし、この後、依存ライブラリのバージョンをあげたりそれ以外にもまだまだバージョンアップ対応は残ってますがとりあえずこの形でSymfonyのバージョンをあげることが自分はできました！
特にComposer周りがメモリ関係色々爆食いしてめんどくさかった記憶があります。