After upgrading from 8.16.3 to 15.5.2, some items are lost, and the error is No repository
report errors: No repository The repository for this project does not exist. This means you can not push code until you create an empty repository or import existing one.
did you follow the recommended upgrade path as described in the documentation, link? BTW -I'm guessing at some point during this stepped upgrade approach you will also need to check and possibly upgrade your PostgreSQL instance version too.
stepped upgrade being: 8.16.3 -> 8.17.7 -> 9.0.13 -> 9.5.10 -> 10.0.7 -> 10.8.7 -> 11.0.6 -> 11.11.8 -> 12.0.12 -> 12.1.17 -> 12.10.14 -> .....etc etc etc .... -> 15.5.2?
Hashed repository storage paths Use hashed storage Use hashed storage paths for newly created and renamed repositories. Always enabled since 13.0. Learn more.
check Hashed repository storage paths config
Looks like we bumped into same issue, I tried the snippets from Gitlab and works https://gitlab.com/-/snippets/2039252