Lightroom Classic stopped working - Windows 10

[BoulderG]

I've recently begun having new troubles with Lightroom Classic and it no longer functions. I'd welcome any assistance and troubleshooting this group can provide: Thank you. This is my first post, so pardon any etiquette transgressions.

Windows 10 Home 64-bit. AMD Ryzen 7 1700 Eight-core processor, 3.00 GHz, 32GB Ram. 446GB SSD C:Drive, all data on E:drive 3.63 GB Toshiba SATA drive (780GB free).

Lightroom catalog is 2.1GB and the whole Catalog directory is 151GB with 333,000 files. All of my images, including Exports, are 2.14TB with 243,000 files.

Been running this computer 14 months. Previously, Lightroom would occasionally stall on startup, but work fine within a few minutes.

I am not aware of any change in behavior before it stopped working one day when I got a message: "Lightroom encountered an error when reading from its preview cache and needs to quit."

I ended up deleting the Previews folder, uninstalling and reinstalling Lightroom Classic several times, and using a known-good backup catalog. No Joy.

Now, when starting Lightroom as User or Administrator, I get "AgNegativeStyleManager_New exception thrown: <AgErrorID>dng_error_write_access_denied</AgErrorID>"

If I click OK, Lightroom starts to load, then again I get "Lightroom encountered an error when reading from its preview cache and needs to quit."

Doesn't matter what catalog I use, if I click the Lightroom icon, on an lrcat file, or the Lightroom exe file, or if I run as User or Administrator.

There may be a couple of other issues with other programs and while I'm pretty novice at computer work, I wonder if this is partly a rights/access issue?

I have run the Windows tools, Glary Utilities, Trend Micro House Call, and Malwarebytes - none find any problems.

I'm unable to use Lightroom Classic and welcome any help you all can provide. Thank you in advance for your assistance!

[GoldingD]

And you did look for a lock file and found none?

[GoldingD]

I may have this keyboard/mouse combo wrong. When starting Lightroom, hold the ALT key down, then mouse click on the startup icon for Lightroom (single or double depending on desktop or taskbar)

An option screen should appear. Select new catalog. See if a new catalog works.

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[BoulderG]

Thank you, david36166309.

The "lock file" is new to me. What is it, where do I look, why is it important?

The keyboard combo uses the FN key in Windows, but it wasn't successful. I rebooted and went to the restored backup catalog. Clicked on a backup catalog from a month ago to start Lightroom (probably not as an Administrator). Got the same AgError message.

The catalog started to load - the directories are starting to appear on the left and there are a lot of the gray boxes that will become thumbnails as the program loads. However, it then stalled out with the Preview Cache error.

Restarted Lightroom again, got "Do you want to choose a different catalog?" and chose Create a New Catalog. Created new catalog on E:drive, same error messages for AgError and for Preview Cache Error. So, no changes.

[GoldingD]

The "lock file" is new to me. What is it, where do I look, why is it important?

The lock file is created when you open a catalog. It's presence prevents a catalog from being opened twice at the same time. Normally it is deleted when you close Lightroom. If Lightroom crashes or otherwise ends abnormaly, the  lock file might still be present, hence you cannot open the catalog.

see: https://helpx.adobe.com/lightroom-classic/kb/lightroom-error-catalog-cannot-be-opened-lrcat-lock.htm...

and be careful to not accidentally delete the catalog.

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[BoulderG]

Thanks! I found and erased lrcat.lock files everywhere I had Catalogs: C:drive, E:drive, and backup F: drive. Erased the lrcat.lock files. Restarted Lightroom.

Same AgError. Lightroom started to load and did not open a Catalog. I went to do so manually, but before I could select one, it gave the Preview Cache Error and closed.

Used FN-Start to open Lightroom, got Select another Catalog. Chose a restored backup catalog (where I just deleted the lrcat.lock file) and selected it. Same AgError. Same as previous - Lightroom is starting to open, showing directories and grey boxes, then stalls out with Preview Cache Error.

Checked, and both C:Users and E:<directory with Catalog> had brand-new lrcat.lock files. Erased them.

Thanks for your help, and what would you suggest next?

[GoldingD]

Use a alternate method of starting Lightroom. I may have the keyboard selection wrong. Press down and hold the ALT key, then without releasing double click on your Lightroom shortcut icon (single click if in taskbar)  to start Lightroom.

 You should be presented with a screen inquiring what recent catalog you want to open, along with some options. You want the new catalog option.

So bring up lightroom having it create a new catalog. See what happens.

Thus is a diagnostic to work around possible catalog corruption.

[GoldingD]

Did a google search on

AgNegativeStyleManager_New exception thrown: <AgErrorID>dng_error_write_access_denied</AgErrorID>"

Gonand look at:

https://www.lightroomqueen.com/community/threads/agnegativestylemanager_new-exception-thrown-agerror...

and from that:

https://community.adobe.com/t5/Lightroom-Classic/Upgrade-to-LR-7-3-now-causes-dng-access-issues-and-...

and

https://helpx.adobe.com/x-productkb/global/troubleshoot-unexpected-behavior-user-account.html

[BoulderG]

I was able to try Creating a New Catalog. Lightroom gives the same AgError message, shows two splash screens, then says Welcome to Lightroom Classic. A moment later, it's Preview Cache Error again.

I don't think this is successfully checking if the catalog is corrupt. Note, I've tried using restored backup catalogs (unzipped) from back when it did work fine, and get the same errors - don't see how those catalogs could be corrupt?

For your Google search:
#1 talks about copying the catalog to a different drive. I've already copied the lrcat file via the backups, and that does not seem to work. I am happy to revisit this option, but currently discarding this path.

#2 discusses permissions. This definitely seems likely, but I don't know how to address the problem. This discussion is from April 6, 2018, and LR 7.2 and 7.3. I have been using 8.4.1. Suggestions on where to start?

#3 gives a number of complex problem solving methods; it'll take a while to work through them. It's from before December, 2017, so I'm concerned if the instructions are still valid?

I'll work through these and report back tomorrow. Thanks for your help.

[GoldingD]

Next up, contact Adobe

[A. Olsen · Accepted solution]

I was having this exact same error and noticed that each time I tried to open my catalog (which I knew to be good) I also got a notice from Windows about "Virus & threat protection - Unauthorized changes blocked."  Once I turned this feature off (who knows how it got turned on in the first place!) and deleted all the temp lock files my catalog opened normally.  Maybe something to check and try?

What to check/turn off on Windows step-by-step found here:  https://help.brother-usa.com/app/answers/detail/a_id/156978/~/virus-%26-threat-protection---unauthor...

[BoulderG]

Wow! Abby, this worked!!

I had been having problems with another unrelated program, too. Both it and Lightroom were listed as 'recently blocked' in the Windows Defender Controlled Folder Access. I allowed both, and they both seem to now be working fine. (Note - I never got the Windows virus and threat protection notices.)

Davidg36166309, thank you for your help. Abby@yasscreative.com - drinks are on me if we ever meet. Thank you both, and big thanks to this forum!

[A. Olsen]

YAY! I'm so glad! 🙌  Have fun with your photography!