I’ve got a fix for this issue coming in the next update of the plugin (which I should be releasing within the next few hours), but you can resolve the issue now by doing these steps:
1. Go to the “hidden” options page: [YOUR URL]/wp-admin/options.php
2. Look for r34icspro_instance and delete its value, then click Save Changes at the bottom. (Be sure not to make any other changes on this page!)
3. Go to the Plugins page, and deactivate and reactivate ICS Calendar Pro.
Also, if you have defined the R34ICSPRO_INSTANCE constant in your wp-config.php file, delete that line before doing any of the above.
This will force the plugin to generate a new “instance” for the new server, and you should be able to enter your license key.
The update to the plugin is adding a Regenerate Instance button to the Settings page, which do the same as all of the above but with a single click. You can wait for that update to be available, if you prefer, but you’ll need to manually download and install the update (it will be version 4.4.10) from here since you can’t access the updates within WP admin without an activated license.
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