P: Error in cloud sync dialog "Some Photos Invalid"

This fix is not working for me. I have followed the steps and some photos are showing, some not and no 'info' is available for them. I have hit delete but to no avail. It seems LR CC  is still trying to sync although I have turned off CC sync - I am getting the blue circle going round for now over 2 days! My photos are stored on an external drive hooked up to a Mac laptop. I have a couple of days ago uninstalled and reinstalled LR CC to try to remedy this but a get the same issue. It may be that my external drive is at fault?? as before I tried this remedy lR was continuing trying to sync. I would like to cancel this sync altogether but seem unable to do so. If I can do this I will hook up another drive and download images to that from LR Cloud. If indeed it is n external drive fault, to complicate matters the I have set in Preferences storage location for originals one the same external drive. Any help out there please?

In the new LR CC, the cloud icon shows an red !. Clicking on the cloud icon, the text 'sommige foto's zijn ongeldig' (dutch for: ' some photos are invalid' How do I find this invalid photos?

This worked for me too - but took a long time to find this post.  All error messages should have more explanation and a link to fix.

Thanks for the info. Like others, I do wish Adobe would let us know how to fix such (important) issues more easily. I don't have the problem now as I went through a much more long-winded way but never mind, I shall certainly print this off and put it in my "More Obscure Adobe Fixes" folder. I am sure many others will use this method too.Thanks again!

Thanks!  This worked for me as well.  Appreciate it.

Thank you, Rick. This worked for me. I wish Adobe would allow us to see which photos are causing the error message much more easily. 

I'm sorry you are having difficulty syncing. Try these steps and let us know it helps:

1. In the My Photos area in the left pane, select the All Photos album.
2. Switch to the Square Grid view (
   

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   ), which displays photos as equal-sized thumbnails along with their flag status, sync status, and rating.
3. While holding down the Alt key (Win) or Option key (Mac), click the cloud icon (
   

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   ). Lightroom CC now displays only those photos that it's trying to sync.
4. Press Ctrl+A (Win) or Command+A (Mac) to select all the photos displaying in the grid and then do any of the following:
   1. Delete the selected photos by choosing the Edit > Delete option and then add the photos in Lightroom CC again.
   2. Apply a flag or a star rating to selected photos.

The syncing issue should now be resolved. To check the sync status, click the cloud icon (

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) at the upper-right corner. 

Same problem. Have you solved it yet? I have checked my entire photo folders and cannot find any hint. It was OK a couple of days ago so what has happened?