Hello,
You should enable temporally the error debug mode in your Joomla global configuration in order to retrieve more details about the error and where it comes from.
CF :
docs.joomla.org/How_to_debug_your_code#Joomla_Debug_Console
The Debug Console can be enabled from the Joomla! Global Configuration, System tab, by setting the Debug System option to Yes. Once enabled the output of the debug plugin will be displayed at the bottom of each page.
That console also display the "debug backtrace" when you have an error ; which allow to understand the nature and the location of the issue.
Regards,
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