500 error when transferring (archived) project

I’m trying to transfer an (archived) repository from one organization to another on Gitlab.com. The source organization is on the free plan, while the target organization is on a paid plan. (Which is exactly the reason I’m transferring this repo.)

I’ve been trying this at various moments in the last few weeks now, but every time I start the transfer I get a 500 error (see screenshot).

The repo is archived, but I guess the same error when I unarchive the repo before the transfer. I have successfully transferred other repo’s (both archived and unarchived) from the same source org to the same target org. This leads me to believe there’s either a bug in GitLab or some hidden property on my repo that prevents the transfer, but I have no idea exactly what.

Since this behaviour has been happening for a long time now, I don’t think any recent issue is to blame here. For example I found Error 500 on Transfer, but that does not seem relevant for my use case.

Hope someone can help!

If someone with access to logs wants a peek: the request ID is 01GDNF3QKDBRN27NHNZJ3GV3CY.

(I guess I could also do an export and import of the repo, but I find a transfer much more convenient)