my thumbnail pictures are gone (all grey)
Lightroom is VERY sensitive to the operating system Color Management Profile installed in your computer.
Grey boxes in place of thumbnail images is 99% a Color Profile problem.
Read the Adobe help- https://helpx.adobe.com/lightroom/kb/photos-appear-black-gray-rectangles.html
(For Windows PCs) Read- Color management settings: frequently asked questions
I don't think its a color management issue.
here are two screen grabs.
all grey thumbnails and all those images have not been linked back to old hard drives.
these thumbnails are on my current hard drive and I can see the images.
with lightroom 5 I was able to see all my thumbnails even if the hard drives are not connected.
I am looking for an easy way to "recover" all my thumbnails without having to link every single image again.
Seems like you had Smart Previews built in Lightroom 5 due to which you did not have to keep your external hard drive always connected.
So, with Lightroom CC as well, you will have to generate the Smart Previews first.
Plugin your external drive first so that images appear up in Lightroom CC. Then, select all the photographs and click on Library menu and choose Previews - Build smart Previews.
Once the previews are generated, then it wont be required to keep your external drive plugged in always.
Following your post and interested to know how you resolve the problem.
Did the Smart Preview re-build work?
LR5 and LR6/cc use two different catalogs and two different cache systems.
LR6/cc will need your external drive attached to create the initial previews in its own cache system. After that you can disconnect the external drive if you want.
Since you migrated the database from lr5 to lr6 and did not move the photos, there should be no need to "relocate" any folders or photos.
unfortunately "Build smart Previews" still does not do the trick. I still have to go in and link each gallery back to the raw files so that the thumbnails show up
was hoping I did not have to do so.
I had the same problem. It looks like it is caused by a corrupt monitor profile. Try changing you monitor profile to sRGB and restart Lightroom to see if this get rid of the problem. If it does re-calibrate your monitor. Worked for me.
NONE of these actually fixed the problem I was also having with missing thumbnails. However, I created a totally new catalog. Then did File Import from catalog. I selected leave photos in place because my .dng files were still fine and in the correct place. All my photos (1,200+) came back instantly with thumbnails and ratings and edits. Boom problem solved, NEXT!