Publishing FGDB unstable behavior (publishing fails or succeeds randomly)

[beau_]

I am publishing zipped File Geodatabases and I am experiencing very random outcomes.

I have multiple FGDBs containing features, tables and relationships classes.

The zipped FGDB is always successfully uploaded, but sometimes after the Feature Layer is created, its item page shows an error message: "There was an error".

Some of my FGDBs are always published successfully and some always fails. All those FGDB are created using the same python code but contains different data.

I tried deleting the relationships on those FGDBs that failed to publish and I could publish them. So it looks like the issue is related to Relationship Classes. But I have some FGDBs with relationships that can be published.

Any idea of what could cause the issue?