Problem merging from fork

In simopenpass, we have a problem with a merge request: https://gitlab.eclipse.org/eclipse/simopenpass/simopenpass/-/merge_requests/16

When we try to merge to our repository from the fork, we get an error message:

Something went wrong during merge pre-receive hook. You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others.
You must be a committer to push on behalf of others. Try again.