Unable to create or update Reports

Hi,

Whenever I try to create a report, I get this message 
"Unexpected exception: Direct assignment to the forward side of a many-to-many set is prohibited. Use widgets.set() instead"
The report is created but without any widgets enabled. And I receive empty reports.
Trying to update the report configuration leads to the same issue :
"Unexpected exception: Direct assignment to the forward side of a many-to-many set is prohibited. Use widgets.set() instead"
Deleting, recreating the reports doesn't solve the issue.

So I have been receiving empty reports for weeks now.

What's wrong with the config ?


Thanks for your help.

Thierry