I’m not fully sure I understand the issue. From the description, it looks like your server is running some sites which don’t work correctly with PHP 5.3 and later. This does not depend on the Skrill plugin, but on something else.
To solve the issue, I reckon that you have two options:
- Ask the developer who maintains the affected sites to address the incompatibility with PHP 5.3. This is what I would recommend the most, as PHP 5.2 has been obsolete since 2011 (even PHP 5.3 is going to be deprecated soon).
- Reconfigure the server to use PHP 5.2. That would bring everything back to the original state, but you won’t be able to use the Skrill plugin.
If you need assistance in fixing the incompatibilities with PHP 5.3, we can help you, but we would not be able to do it free of charge, and standard support rates would apply.
