Internal error 500

I’m moving site from a subdomain to another domain. It’s not working. The restore on the new domain completes. But when the page reloads either:

1. Internal Server Error. The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator at to inform them of the time this error occurred, and the actions you performed just before this error. More information about this error may be available in the server error log.
2. Or the wordpress login page appears but it’s back to the subdomain, back where I started. Any ideas?