Troubleshooting bugs on the website under OpenCart

Is there a site with OpenCart engine 3.0.2, which gave HTTP 500 ERROR. Judging by the error log has filled the cache due to some bug and problems with Russification. Need to fix bugs and bring the website up and running on our hosting, because it has already done much work on a project and lose it does not.
Will have to chat with me, zero in programming, be prepared. For the same reason I can't give a more precise TOR. The time and cost can be discussed.