(12:57:10) | [DEBUG] Load requested for plugin which is already loading: Rustcord
(12:57:10) | [DEBUG] Load requested for plugin which is already loading: Rustcord
(12:57:11) | Rustcord was compiled successfully in 1656ms
(12:57:12) | Unable to find main plugin class: Rustcord
(12:57:12) | No previous version to rollback plugin: Rustcord

Any time you see "Unable to find main plugin class", that means that the file was likely not valid or incomplete, so it could not be loaded. I'd suggest download it again.

thank you .. solved .
the problem was my ftp client its not uploading files properly .