Smart Previews Not Loading

[DaBrownCO]

My Smart Previews are not loading when I open a folder in which my originals are stored in an external hard drive that is off-line. In each of two folders I've opened, a handful of Previews load, but that's it.

I appreciate any help you can offer.

David

[DaBrownCO]

I should add that the Previews I see appear to be photos I've edited or rated although I am not 100% certain.

[Jao vdL]

How sure are you that you actually have smart previews of these images? It should say Original+Smart preview under the histogram when you select the image in Library.

[DaBrownCO]

Yes the photos have Original + Smart Previews under the histogram. 

[Jao vdL]

Weird then it should work and it should revert to the smart previews automatically if the originals are off line.

[JohanElzenga]

Sounds like your previews cache may be corrupt. Open your catalog folder and move 'catalogname previews.lrdata' out of it. Leave 'catalogname smart previews.lrdata' in place. Start Lightroom and see if this helps. Initially you will see no previews at all, but then Lightroom should start rebuilding the cache so they'll appear one by one.

[DaBrownCO]

So just to be clear, even though it's my Smart Previews that aren't loading, I should move the previews.lrdata folder. Thanks.

[Jao vdL]

Johan is referring to removing the separate smart previews file you'll find next to your catalog. You will have to recreate them after that. 

[JohanElzenga]

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Jao vdL wrote:

Johan is referring to removing the separate smart previews file you'll find next to your catalog. You will have to recreate them after that. 

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No, I am not referring to removing the smart previews file! What I am saying is this: Your previews.lrdata (not smart previews.lrdata) file is probably corrupted. That is why Lightroom can't add new previews to it. So what you need to do is remove the previews.lrdata file, so Lightroom can rebuild it using the smart previews. So once again: Remove the previews.lrdata, but keep the smart previews.lrdata.

[Jao vdL]

Sorry misunderstood what you said. I guess the question we should have asked is whether there are no previews in Library in which cases you are right, the jpeg preview database is not good and you should remove the normal previews. If the images are not loading in Develop but there is a preview in Library than it is the smart previews that are bad.

[JohanElzenga]

No, we should not have asked that. The OP already told us that there are some images with previews, but other images remain blank. He said "In each of two folders I've opened, a handful of Previews load, but that's it." That is a clear sign of corruption of the preview cache. The previews that load are up-to-date, so Lightroom can use them. The other previews need to be regenerated for whatever reason, and because the cache is corrupt that doesn't happen. That is far more likely than dozens of corrupt smart previews. And it is easy to verify by removing the previews from the catalog folder. If Lightroom successfully rebuilds the previews then I was correct, if it does not manage to rebuild the previews then the smart previews are somehow corrupted.

[DaBrownCO]

Thanks both. I had a busy weekend, but will try the fix that Johan suggests later today. 

[DaBrownCO]

Okay, I did what @JohanElzenga suggested. In Library view, when viewing in Grid mode, I don't see any images. However, if I open an image in Develop, the preview does open. Does this help give some insight as to what my problem may be? Thanks.

[JohanElzenga]

It only makes it stranger. Check this: Apple changed the security requirements in MacOS Monterey and later. Go to MacOS 'System Settings - Security & Privacy' and add Lightroom Classic and Photoshop to "Full Disk Access". Click on the lock icon to unlock the settings, then click on the plus icon to add Lightroom Classic and/or Photoshop if it isn't already listed. If it is listed, then just enable the checkbox. See also Quick Tips: How to give Full Disk Access to Lightroom Classic on macOS

If that is already done, then may reset the preferences: https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/

[DaBrownCO]

I did add Lightroom Classic to give Full Disk Access. I also went ahead and reset preferences. Is there a way to get to my set of Preferences that I had before resetting? I did copy them to my Desktop before doing anything. Also how long should I have to wait until I start seeing the Smart Previews? Finally, do I have to be connected to the external hard drive that contains the Originals in order for the Smart Previews to build?

[JohanElzenga]

To start with the last question: No, not for rebuilding normal previews (the thumbnails you see in the grid). But if you need to rebuild smart previews themselves, then you do need the originals. Because you see them in the develop module, the smart previews cannot be corrupted however.

You should not have to wait at all to see thumbnails being generated. As soon as Lightroom Classic starts, it should regenerate those thumbnails that are visible in the grid. Be aware that thumbnails that a currently not visible in the grid will not be generated until you scroll the grid so they become visible.

If resetting the preferences did nothing, then you can simply replace the new preferences by the copy you saved. I believe the link I gave you also mentions the location of the preferences. By the way: I have found that sometimes you need to delete the preferences rather than use the key combo to reset them on start. Resetting clears the contents of old file, but keeps using it, so it that file is corrupted then resetting may not always solve it.

[DaBrownCO]

I did do the manual delete of the preferences from the start. I'm wondering if I should uninstall and reinstall Lightroom. Thoughts? Thanks

[JohanElzenga]

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DaBrownCO wrote:

I did do the manual delete of the preferences from the start. I'm wondering if I should uninstall and reinstall Lightroom. Thoughts? Thanks

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You can do that but I'm 99% sure that's only a waste of time. This has to be a catalog issue, not an application issue. Is the disk with the original images connected? If not, then try first if that changes anything. If it does, then this might be a problem with the smart previews after all.

[DaBrownCO]

It's not so easy as that as I have my catalog on Dropbox and because they are so large, I can only make about 4 months of images available at a time due to hard drive space. I'll try that though.

[Jao vdL]

>I have my catalog on Dropbox

Ooof! That can be a real problem! I wouldn't be surprised if this is part of the issue. If you do this, you have to make absolutely sure that the files are always actually on the machine. By default, dropbox offloads files not in active use from the local machine and replaces them with a zero-byte file that only will get loaded if you try to access them. This breaks with many applications including Lightroom Classic. So you need to make sure the folder of previews and the catalog are set to be available offline and even then you might need to revisit that quite often as that setting is not sticky if new files (e.g. new previews!) are added to a folder. You can make this work but it is fraught with major pitfalls to put your catalog on a cloud service folder. 

[Jao vdL]

Oh and needless to say this completely breaks things if you happen to not have internet access at some point!

[JohanElzenga]

Dropbox is indeed almost certainly the explanation! If you make the original images online only, then Lightroom will think that they are local because of that zero-byte file. So instead of using the smart preview, Lightroom will try to access the original to rebuild previews. In the past that would work fine. There is an issue with Dropbox on the latest versions of MacOS however, where third party apps like Lightroom cannot download online only files, only the Macintosh Finder can. So that is why Lightroom cannot rebuild previews. It ignores the smart previews because it thinks it doesn't need them, and then chokes on trying to access the original. But when you switch to the develop module, it will use the smart preview, most likely because you set that option in preferences - performance.

[DaBrownCO]

Hmmm. I know I have to make files off-line now to edit, but I could always see my Smart Previews even for files with zero bytes.

[JohanElzenga]

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DaBrownCO wrote:

Hmmm. I know I have to make files off-line now to edit, but I could always see my Smart Previews even for files with zero bytes.

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The problem is that you cannot tell Lightroom to use smart previews for building thumbnails if originals are available. You can tell it to use smart previews for editing, but not for thumbnails. And that is why you see what you see.

[JohanElzenga]

And the reason why it worked in the past is because this is a Dropbox issue that was introduced with MacOS Monterey if I remember correctly.