Please make sure the following things to avoid this error.
- Component file name as same as the component folder name
- The component name is NOT the same name as the vs code project folder name
- The name of the LWC component starts with a lower case letter
このエラーを回避するには、次の点を確認してください。
- コンポーネントファイル名はコンポーネントフォルダ名と同じ
- コンポーネント名はVSコードプロジェクトフォルダ名と同じではありません
- LWCコンポーネントの名前は小文字で始まります
Sandbox
- Updating Account returns DUPLICATE_VALUE, duplicate value found: duplicates value on record with id:
It was resolved in the end with an SF Support Case, and they 'fixed' (with no real detail) some records in the Sandbox. I asked for more info but nothing useful was provided, and was told it was something I couldn't have done anyway.
So, sounds like some sort of data corruption when the Sandbox was refreshed.