If you're encountering an issue with Slave DNS Manager after updating Plesk, specifically the error message "Invalid JSON data input: ''," there may be a configuration or data issue causing the problem. Here are steps to help troubleshoot and potentially resolve the issue:

1. Check for Known Issues:

   • Verify if there are any known issues or compatibility problems with Slave DNS Manager in Plesk 18.0.52 by referring to release notes, forums, or Plesk support resources.

2. Review Configuration:

   • Go to "Extensions" > "My Extensions" > "Slave DNS Manager" and review the configuration settings. Ensure that the settings are accurate, including the connection details for your slave DNS servers.

3. Reconfigure Slave DNS Manager:

   • Try reconfiguring Slave DNS Manager by going to "Extensions" > "My Extensions" > "Slave DNS Manager" > "Go to Extension" > "Reconfigure." Follow the prompts to set up the extension again.

4. Check Connection to Slave DNS Servers:

   • Confirm that Plesk can communicate with your slave DNS servers. Make sure there are no network issues, firewalls, or access restrictions blocking the communication.

5. Verify JSON Data:

   • The error message suggests an issue with JSON data. Double-check that there are no invalid characters or formatting errors in the JSON data being sent to or received from the slave DNS servers.

6. Check Logs for Details:

   • Review the logs related to Slave DNS Manager for any additional error messages or details that might provide insight into the problem. You can find logs in Plesk at "Tools & Settings" > "Plesk Logs."

7. Update or Reinstall Slave DNS Manager:

   • If available, consider updating or reinstalling the Slave DNS Manager extension to ensure you have the latest version compatible with Plesk 18.0.52.

8. Contact Plesk Support:

   • If the issue persists and you're unable to find a resolution, consider reaching out to Plesk support for further assistance. They can provide specific guidance or escalate the issue if necessary.

9. Restore from Backup (if applicable):

   • If you have a backup of your Plesk environment from before the update, you might consider restoring it to see if that resolves the issue. Be sure to back up your current configuration before attempting a restoration.

10. Community Forums and Resources:

    • Consider checking the Plesk community forums or other online resources. Other users may have encountered and resolved similar issues.

Always proceed with caution when making changes to your server configuration, and ensure you have backups in place before attempting significant modifications.