I found the discussion already and copied the config.lua file into the Lightroom folder.
But Restart Lightroom doesn't fix the problem.
The backup problem raised after updating vom 6.? to 6.8
I use Windows 10 Version 1511.
Thanks for help
This is a known issue and we are working on it. Please try again and ensure you have followed all steps mentioned in the workaround.You may also post your issue here Lightroom: Erroneous warning message on Catalog Backup | Photoshop Family Customer Community.
I will get in touch with the concerned team to discuss this.
now I got it. I put the file in a wrong Lightroom folder. Now it seems that all works korrekt.
Thanks for the update.