Some photos out of focus during during flagging process

[bunkieboy]

I have LR 5.7.1. When I'm in library and going through my pictures, flagging some, I''ve suddenly run into a problem where some of my photos, once you double-click them in the loupe view to get a bigger view, are way out of focus. They don't appear to be out of focus in the loupe view .I've never had this problem before. This is in keeping with my changing to another catalog because for my regular catalog I got the message "LR encountered an error when reading from its preview cache and needs to quit". (an issue I've dealt with before but will probably need help with again.)

Also--for the first time in my use of LR, in the tray I've gotten on a couple of photos an exclmation mark indicating I've made some mistake with a particular photo. Now what does that mean?

Thanks,

Al Marotta

[AxelMatt]

I have LR 5.7.1. When I'm in library and going through my pictures, flagging some, I''ve suddenly run into a problem where some of my photos, once you double-click them in the loupe view to get a bigger view, are way out of focus. They don't appear to be out of focus in the loupe view .I've never had this problem before. This is in keeping with my changing to another catalog because for my regular catalog I got the message "LR encountered an error when reading from its preview cache and needs to quit". (an issue I've dealt with before but will probably need help with again.)

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By @bunkieboy

It seems that there's a problem with the preview cache. Please delete the cache so it can be rebuild automatically. Then check if it's work.

Lightroom error on preview cache or displays gray thumbnails (adobe.com)

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Also--for the first time in my use of LR, in the tray I've gotten on a couple of photos an exclmation mark indicating I've made some mistake with a particular photo. Now what does that mean?

Thanks,

Al Marotta

By @bunkieboy

The exclamation mark means that LR can't find the original file of the image.  This can happens if the image files saved on a external hard drive and this drive isn't connected. Or it's connected with another drive letter. Or you have deleted the images using the Windows Explorer.

See here how to fix:

Lightroom thinks my photos are missing—how do I fix it? | The Lightroom Queen

Adobe Lightroom - Find moved or missing files and folders (computer-darkroom.com) 

[bunkieboy]

Thank you, Axelmat, for your kind help. I solved my problem by going to the link you gave me and trashed the db and root pixel files. Doing that, my focus problem and the black exclamation problem disappeared. Unfortunately I have an addtional problem. In an effort to solve my problem on my own (before I got help on this forum, I switched from my usual catalog to a different one. This secondary catalog did not give me the message about error reading preview cache and I was able to use it for the photos I downloaded.  The problem is, I still get the error reading cache message on my primary catalog and can't use it.  I have placed into the recycle bin the the root pixels db and other db in another preview folder, but to no avail. 

Appreciate any help,

Bunkie