The issue was due a sandbox refresh which was running for quite long without any error.
この問題は、エラーなしで非常に長時間実行されていたサンドボックスの更新が原因でした。
The error message you are seeing is a common error message in Salesforce DevOps Center. It can be caused by anything from installing DevOps Center in the wrong org edition to an issue when pulling changes from an existing work item. One possible cause of this issue is due to event processing delays, which can create a duplicate Work Item Promote (WIP) record. To resolve this issue, you can find and delete the duplicate Work Item Promote record. If this does not resolve the issue, you can try logging out of GitHub and logging back in again.
Refer this:
表示されているエラー メッセージは、Salesforce DevOps Center でよくあるエラー メッセージです。この問題は、間違った組織エディションに DevOps Center をインストールしたことから、既存の作業項目から変更を取得するときの問題まで、あらゆることが原因で発生する可能性があります。この問題の考えられる原因の 1 つは、イベント処理の遅延により、重複した作業項目プロモート (WIP) レコードが作成される可能性があることです。この問題を解決するには、重複する作業項目プロモート レコードを見つけて削除します。これでも問題が解決しない場合は、GitHub からログアウトして、再度ログインしてみてください。
It seems to be a storage limit.
we ran into this same issue this summer, when testing the beta, and decided to wait until GA to carry on our tests.
This issue is a known issue of the beta. I have understood that once GA, DevOps Center should not consume any storage, but have asked confirmation.
To clarify, we unfortunately will not have addressed the storage limit situation with the GA. We're planning to look at this post-GA and hope to have a solution some time next year. As we get better understanding of the solution we'll be able to update with more precision on expected timeframe.
https://trailhead.salesforce.com/trailblazer-community/feed/0D54S00000HEFMySAP
Thanks everyone who chimed in... I was able to fix my error with some guidance from this thread... https://trailhead.salesforce.com/trailblazer-community/feed/0D54S00000HEFMySAP
For me, completely uninstalling the app and reinstalling it worked.
Here's the documentation to help with stalled promotions:
https://help.salesforce.com/s/articleView?id=sf.devops_center_promotion_stalled.htm