Gallery could not be saved! Please try again.

After upgrading my website(s) to Joomla 4 I and upgrading SIGE to the Joomla 4 compatible version 4.2.4.0.PRO I get the message "Gallery could not be saved! Please try again".when I try to create a new gallery from the component. It works on a website where I had created galleries in the joomla 3 version before upgrading. It doesn't work on websites where I create a gallery for the first time in this component. It is not a database problem, because I am able to create the record manually in the database and update it afterwards through the SIGE component. As a test I disabled the .htaccess file to check if that could be the problem. Still unable to create a new gallery. I uninstalled SIGE 4 and re-installed. Same problem. I am out of solutions. If anyone can point me in the right direction I would appreciate it. It is probably something simple.
Both SIGE-plugins are enabled and work fine.

Regards
John Dohmen

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