Hi,
I contacted the administrator, he said that the problem is on the www side. I don’t know much about it and I don’t know how to go about “identifying the problem”. Everything is up to date, except for the required plugins there is sucuri and dupicate page. Could the problem be caused by any of these plugins? Importantly, the 500 error problem only appears when trying to edit the main page of the service. The other pages of the service can be edited without a problem.