P: Preview Thumbnails are Black

See the article posted by Rikk Flohr above.

Just updated Lightroom CC 2015 last night (10th Oct) on Windows PC and a laptop. All photo imports now just black out as they import. Previously imported photos are fine.

1: this problem only started when I opened LR CC2015.2 the first time and the squares were black and then changed to gray automatically.

2: I did not touch my monitor settings which were working perfectly with CC2015.1 but now when I roll back to CC2015.1 it too shows only gray squares.

3: I have reinstalled my LR 5.7.1 and it is working perfectly!!! fast and NO GRAY OR BLACK squares.

If the preview cache for 2015.2 and 2015 .1 is corrupted I can only conclude that this happened with the 2015.2 install.

where do I find the preview cache and how do I rename it?

I'm an old generation photographer and not a geek.

This thread is about Black Thumbnails not Gray. Gray thumbnails are usually symptomatic of a bad monitor profile or a corrupt preview cache. Try recalibrating your monitor.

If changing the calibration profile or recalibrating doesn't work, you should look at renaming your preview cache.

sorry, but this work around does not work for me!

In the library mode: both the grid view and the thumbnails remain grayed out.

In the develop mode: the photos appear in the workspace but remain grayed out in the thumbnails. I can only change/select the photo by using the next/back arrow keys. not the most efficient workflow........

It is the same for existing and/or new imports.

Victoria, thanks. 80-90% of my photos are JPG, mostly from a Fuji camera. Since these generally need little or no adjustment, I decided to leave Auto Tone off in the preferences panel as you suggested, but not apply it manually (most of the time). If it weren't for the bug and your suggestion, it might have taken me (an Aperture refugee) a long time to realize that Auto Tone could be suppressed.

These suggestions worked on an existing import where the problem occurred and also prevented the dark previews on a new import trial attempt. Thank you!

LR CC 2015 v2 after import from camera card as well as hard drive folder displays all images with dark -5 exposure in the develop module. Slider adjustment has no effect. Solution seems to be to apply the Auto Tone function, which results in a viewable thumbnail and image display. Running on MacBook 2008 with 8GB of ram and fully updated El Capitan op sys.

oh dear, back to square one......the little man inside my computer is very fickle......now I have gray squares on nthe film strip and only the photo on screen shows up in the thumbnail......am going sorting by clicking move button on work space.
Oh well back to 5.7.1