Solution for 500 Server Error
INSTALLING ADD-ONS
Open: file: /app/Http/Controllers/ModuleController.php
1 - Go to line 118.
2 - Replace this: $addon->package_name = $data['package_name'];
3 - With this: $addon->package_name = $data['package_name'] ?? null;
There you go my friends! Now you can install and activate all the modules!