There’s no real versioning of plugin. You have to delete old V.1.2. Then download and install new 1.2. Your preferences will be kept. This worked.
Deactivating, updating, reactivating solved the problem. But there was neither a dev environment nor a change of domain name. If your solution runs like that in future updates I can cope with this.
Thank You.
Fix seems to work on the first sight. Thank You!
