"Lightroom encountered an error when reading from its preview cache and needs to quit"

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I've encountered this error message,"Lightroom encountered an error when reading from its preview cache and needs to quit" while editing photos in Lightroom the past two days. I've never experienced this error message until recently. I searched online for help and came across this: https://helpx.adobe.com/lightroom/kb/lightroom-gives-error-preview-cache.html. I followed the steps and it worked for a bit but the problem is back. 

The issue seems to come and go, it often starts after the program has been open for a few hours straight or overnight. 

I reached out to Adobe Forum and came across the same information. Additionally, someone stated that there might be an issue with my hard drive. I havent found information on how to fix this issue or to test that the hard drive is the issue (though the hard drive barely has anything on it, it relatively new and hasn't had any issues). Only lightroom classic is having issues. Does anyone have any information or experience with this issue?

The issue didn't happen before updating the program recently. 
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amanda del-grosso

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Posted 4 months ago

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James Hess

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Did you delete the lrdata file and restart Lightroom? What was the result if you did?
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amanda del-grosso

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I did delete the file and restart lightroom. The issue stayed away then came back an hour or two later. It's getting quite frustrating. 
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Arnold Hoddevik

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You are probably running some sync service , that includes the catalog folder and previews. Do not sync files while in use. Sync after you quit Lightroom. Previews should not be synced anyway, because it is not necessary, and it is waste of backup disk space and line capacity.
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Petri Sirkkala

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I think Arnold referred to some third party file syncing. Like Dropbox or such. Also a backup solution might cause something like this, especially on pessimistic file locking file systems such as Windows has.

I have not had issues before nor now with cache corruption. Reason that LR is having these while other software might not is that there is a ton of data moving there.

Do not position the library on any network share or such, it will not work either. Naturally your photos may be wherever you feel them need to be tho.

If your library is on an external disk, try relocating it to an internal one to see if the issue is with that drive only.
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Arnold Hoddevik

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Yes, it is not syncing inside of Lightroom, but any backup or cloud based, like iDrive, DropBox or any third party sync software. They all usually react upon changes in files and folders included in sync operation. It is hard to be more precise, because there are several choices.
I know very well this problem from a user group I am running in Norway. Actually it is quite common. When users turn off the syncing while Lightroom is running, the problem is gone. 
Anyway, you should not sync previews. The are huge, and syncing preview data creates a lot of wasted traffic. If preview data are missing, Lightroom creates new when needed.
The problem is allways connected to the preview data.
(Edited)
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amanda del-grosso

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I doubled checked in Lightroom Classic and syncing is off and has been (it has never synced anything). I also don't have any cloud based backups on my laptop like Dropbox, etc.
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Petri Sirkkala

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Try making a new user account on the machine and testing there. 

Also try copying your library to another drive (that is directly connected to your machine) and opening it from there.
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Arnold Hoddevik

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As I wrote, this is not used by syncing inside Lightroom Classic CC, (syncing collections to LR Mobile/CC). The message says "error when reading from its preview cache..", which means the preview file is corrupt. (on Mac it is a file with the same name as the catalog file. If the catalog file is "Lightroom Catalog.lrcat", the preview file is "Lightroom Catalog previews.lrdata").The error is corrected by 
1. Delete the Lightroom Catalog previews.lrdata file
2. Stop the service that is accessing the file while you are using Lightroom.
3. Start Lightroom again, and Lightroom will start building new previews on demand.

Why does the preview file get corrupted? That is because some service is trying to access the file while it is used by Lightroom. Usually that is caused by som third party cloud based syncing service or local backup software. Since you do not have any cloud based sync service, it could very well be Time Machine making backup. When you find this software or service, you will solve your problem. 

When the message keeps coming back, you need to investigate further.
Edit. There could be one other reason - disc error. To find out about this, try to copy  the catalog file to a different folder or disc, and double click on the catalog file in Finder, to start Lightroom and open the catalog file from a different location.
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