VcsException: Missing delta base

I've got Upsource-2019.1 installed on a server and for some of our projects everything is working fine. Nevertheless, some others are not parsed anymore, and when I reset them it fails with an error in the log file :

Failed to construct graph for XXXX:. Failed to collect commits graph for XXXX:. jetbrains.buildServer.vcs.VcsException: Missing delta base 0408bf30437936d35f6434baea2fb1e2624c9

The project is a git project on gitlab, configured with a HTTPS URL and a user/password authentication. Below is a extract from the stack trace.

Thanks for your help !

Guillaume

Caused by: org.eclipse.jgit.errors.MissingObjectException: Missing delta base 0408bf30437936d35f6434baea2fb1e2624c9203
at org.eclipse.jgit.transport.PackParser.resolveDeltasWithExternalBases(PackParser.java:815)
at org.eclipse.jgit.transport.PackParser.parse(PackParser.java:515)
at org.eclipse.jgit.internal.storage.file.ObjectDirectoryPackParser.parse(ObjectDirectoryPackParser.java:194)
at org.eclipse.jgit.transport.PackParser.parse(PackParser.java:448)
at org.eclipse.jgit.transport.BasePackFetchConnection.receivePack(BasePackFetchConnection.java:762)
at org.eclipse.jgit.transport.BasePackFetchConnection.doFetch(BasePackFetchConnection.java:363)
... 33 more