I went through all possible solutions I found in the internet including renaming htaccess file and increasing memory limit. I still endlessly recieve Internal server error.
I purchased Economy Windows Hosting with Plesk and tried to move my website (with premium wordpress theme) from local server using Duplicator and received Internal Server Error. I tried to move using FTP - the same result. Ended up trying to install wordpress and clean theme - nothing. Theme itself is not extremely heavy - only 12 mb without plugins. I don't know what else I can do. Any suggestions? Or I have to try my luck in refund?
Without knowing how your site is setup it could be a number of things cause those errors. 😉 It may not be memory as you are assuming.
Could it be a path issue between where the files are stored locally compared to where you're migrating to on the server?
"Could it be a path issue between where the files are stored locally compared to where you're migrating to on the server?"
Doubt so. I tried to install wordpress and theme I bought. Wordpress works fine until I activate this theme after which I recieve Internal server error.
If WordPress works fine until you active the theme -- the theme is clearly causing a conflict. Did you contact the theme developer and explain the situation to them? They know their code best and would know if there are any bugs and/or conflicts with other plugins you may have in place.
To troubleshoot further...
=> Is your theme tested up to 4.8.1?
=> Does the theme do the same with all plugins deactivated? That would confirm it is the theme as well.
=> Did you try activating the most recent WordPress theme Twenty Seventeen? If you do and everything goes smoothly there -- again, that points to your theme.