Internal Server Error The server was unable to complete your request. If this happens again, please send the technical details below to the server administrator. More details can be found in the server log

When you upgraded PHP, was it the process where you could choose between the local copy and replacing it in Raspbian? Posting results from nc-info will be helpful.

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What device are you using?
Have you checked nc-info in the :4443 webui or ncp-config?

You can try these steps below from the ncp docker guide to address the permissions issue.