Family Historian User Group

Hi
when I backup using Medium or Full Backup I get a message saying that it is unable to open the above file for backup. I can skip this file and continue with backup but I can't find any information about the consequences of doing this. Are there any?

I have checked other topics in this forum but can't find any replies that address this particular issue. The ThumbCache file is in the folder indicated by error message and is 1.99Gb

Any help or advice would be appreciated

The Thumbcache.dat can be ignored during backup, it can even be safely deleted, as it will be rebuilt everytime FH is opened.

The ThumbCache.dat file holds thumbnail images of all your Media image files.
It is not important if it is missing, because as John says, it is automatically rebuilt by FH.

In fact some users have found it useful to delete it from time to time, and when it gets rebuilt it is significantly smaller.
This suggests that FH does not purge unused thumbnails from the file, so it just keeps growing in size.

A related setting is Tools > Preferences > General tab, Advanced button, Thumbnail images.
Click the Help button for an explanation of the options.
Some users find it better to set it to Load When Needed.

If you Search for ThumbCache in the Forum search box above, then several past topics are listed.

BTW:
My Media folders holds about 1,000 files (mostly images) and is about 800MB in size.
The ThumbCache.dat file is about 35MB is size.
Since thumbnails should be smaller than their full images, your 1.99GB file suggests your Media is perhaps 10 times that in size. If it is not that large, then deleting your ThumbCache.dat file will be worthwhile.

Thanks for the explanation.
I have made a lot of changes with images etc so I will delete the file and see if it does rebuild as a smaller file.

Thanks again.