Issue backing up catalog

[Seabreezeof]

LR 6.14 / Windows 10 / I am getting a pop up window when I try to backup catalog It says LR encountered an error when reading from it's preview cache and needs to quit. Also says LR will attempt to fix the issue next time it launches. However it does not fix the issue, as I keep getting the same message every time I try to back up

[dj_paige]

Delete the preview cache. Look in the same folder as your catalog file. The preview cache is a subfolder whose name is your catalog name and it ends with .LRDATA (might be lowercase). Delete the .LRDATA subfolder. DO NOT DELETE ANYTHING ELSE.

[GoldingD]

https://helpx.adobe.com/lightroom-classic/kb/lightroom-gives-error-preview-cache.html

[Seabreezeof]

Thank you dj_paige  and  GoldingD 

I will give your recommendations a try 

I wonder what causes the issue in the first palce, any idea?