The error message "Cannot get extensions list for version XX" typically indicates an issue with the CloudLinux PHP Selector. This error message suggests that there may be a problem retrieving the list of available PHP extensions for a specific PHP version.

Here are some steps you can take to troubleshoot and potentially resolve this issue:

1. Check PHP Version: Make sure that you've selected a valid and installed PHP version. If you're trying to select a PHP version that hasn't been installed or is not available on your server, you may encounter this error.

2. Verify PHP Installation: Ensure that the selected PHP version is properly installed on your server. You can do this by using the php -v command in your terminal.

3. Check PHP-FPM Configuration: If you're using PHP-FPM, ensure that the PHP version you're trying to select is properly configured in your PHP-FPM pool configuration.

4. Verify PHP Extensions: Make sure that the required PHP extensions are installed for the selected PHP version. You can use the php -m command to list all installed PHP extensions.

5. Check PHP Selector Configuration: Verify that the CloudLinux PHP Selector is properly configured and that there are no misconfigurations that could be causing this issue.

6. Check for Updates: Ensure that your CloudLinux installation, including the PHP Selector, is up to date. Outdated software can sometimes cause compatibility issues.

7. Review Logs: Check the system logs for any error messages related to the PHP Selector. This can provide additional information about what might be causing the issue.

8. Contact Support: If you've tried the above steps and still encounter the error, it's advisable to contact CloudLinux support for further assistance. They may have specific troubleshooting steps or be aware of any known issues related to the PHP Selector.

Please keep in mind that specific steps and solutions may vary depending on the exact configuration of your server and any recent updates or changes made to your environment. Always refer to the latest CloudLinux documentation or contact their support for the most accurate and up-to-date information.