usalabs wrote
install2.php Reading 8 bytes failed = The process cannot access the file because it is being used by another process.
This error in conjunction with Error 500 is probably due to your script requiring a lot of time to execute.
So you'll probably have to extend the timeouts and the maximum execution times to allow for more running time before PHP hangs the script and/or Abyss Web Server thinks the script is blocked and kills it.
The settings to alter are explained in
https://aprelium.com/forum/viewtopic.php?p=648995#648995 .