Something went wrong during merge pre-receive hook

We want to merge a simple commit https://gitlab.eclipse.org/eclipse/simopenpass/opvisualizer/-/merge_requests/2 but we receive the following error message

More information is available at: https://api.eclipse.org/git/eca/status/5ca3322bbf2fc90ecd532910626c31ab/ui

The ECA was signed by the author, so we don't know where the problem is.