Why does LR write to jpgs even when I haven't updated anything?

Report · Jun 14, 2020

I have my LR catalog set to "Automatically write changes into XMP."

However, Lightroom sometimes writes changes to jpegs, completely at random, even when nothing related to those images has changed. Obviously if I make an actual change - i.e. adding keywords, developing, etc - I would expect (and desire) it to write those changes to the file; however, sometimes I'll do nothing other than launch & quit LR, and it'll randomly modify a handful of files that I haven't looked at or touched in years. Sometimes I'll copy my catalog to another PC (which shares access to the same network device housing the photos), and simply opening the catalog will cause it to start writing changes into thousands of my files. Sometimes I'll import a new directory, and it'll suddenly start writing changes into files in a different/unrelated directory. There seems to be no rhyme or reason to when or why it does this.

I'd like for it to only actually write changes when...something changes. Is that not possible? Why does it exhibit this extremely odd & unpredictable behavior?

Using LR Classic CC 8.0 on Windows.

Report · Jun 15, 2020

XMP sidecar files are only created for RAW files. For most other files the edits are written into the file itself in a special section and can only be read, and shown, by the same program and or in the case of LR and ACR by either of those 2 programs.

This happens for DNG, TIFF, PSD and JPG.

If you view the JPG in some other editor or viewing program you will not see your edits made in LR.

Report · Jun 15, 2020

That does not answer the question. The OP knows that. The question is why Lightroom sometimes writes changes to XMP when there are no changes. This seems to be a long standing bug. Lightroom also sometimes reports that the metadata have been changed by another application, even if they haven't been changed. By the way; Lightroom Classic 8.0 is pretty old. Why don't you update regularly? The current version is 9.2.1.

-- Johan W. Elzenga

Report · Jun 15, 2020

>>This seems to be a long standing bug.

So it's a known bug? Do you have some reference of that - i.e. an issue on a bug tracker that I can subscribe to & be notified if/when it's finally properly addressed?

>>By the way; Lightroom Classic 8.0 is pretty old. Why don't you update regularly? The current version is 9.2.1.

I used to keep up to date, but gave up on doing so specifically because Adobe (for some reason) decided to start making it overly cumbersome to do so - as I documented here, two years ago: https://feedback.photoshop.com/photoshop_family/topics/lightroom-classic-cc-offline-updater.

Report · Jun 15, 2020

What???

The Adobe Creative Cloud Desktop App, is hardly hard or cumbersome to use. You do not use it to keep your LRC up to date? Heck, it can be set to do that automatically.

Manually, just bring it up and click on the LRC icon, boom, done.

Being as you apparently have not updated LRC since v8 something, is your Adobe Creative Cloud Desktop App up to date? a problem existed way back about the v8 time.

Heck, v8 was buggy, and you wonder why a bug still exists?

Report · Jun 15, 2020

>> What??? The Adobe Creative Cloud Desktop App, is hardly hard or cumbersome to use. You do not use it to keep your LRC up to date? Heck, it can be set to do that automatically. Manually, just bring it up and click on the LRC icon, boom, done.

Apparently you didn't check the other thread, but in (very brief): it's because my LR PC is airgapped. It used to be simple to download an updater & install, which I did regularly. But Adobe suddenly stopped posting proper update installers, instead forcing everyone to use Creative Cloud - thus, the only way to update is to have a (fast+unmetered) connection directly on the PC on which you want to run LR. There are other specific reasons & scenarios described in that thread, but that's the crux of it. I tried multiple times to contact them & understand why they suddenly started refusing to post proper standalone update installers, but when it became clear that was the case, I stopped updating as regularly.

>> Heck, v8 was buggy, and you wonder why a bug still exists?

Does that mean the bug is no longer there in v9? 🙂

Report · Jun 15, 2020

Exactly what file gets updated? A JPEG you did not touch? A preview file? As for an xmp, well not associated with a JPEG. anything that would be written to an xmp file associated to a RAW file is instead written right into a raster file, as stated xmp sidecar files are not created for raster images.

Do you shoot exclusively JPEG, or perhaps RAW + JPEG. If you are looking at a xmp file, then it would be against a RAW file of similar name.

Report · Jun 15, 2020

>> Exactly what file gets updated? A JPEG you did not touch?

Many JPEGs I did not touch. It applies to images shot exclusively as jpeg, so there is no raw and no sidecar xmp.

Report · Jun 15, 2020

There are many reports of spurious metadata conflicts, where LR thinks the metadata has been changed both by LR itself and an external application, e.g.

https://feedback.photoshop.com/photoshop_family/topics/still-no-answer-to-metadata-has-been-changed-...

I looked just now in the feedback forum (where bugs get reported) and couldn't find any specifically about LR spuriously writing metadata or the metadata status indicator spuriously showing that the file needs to be updated.

In the past I had a few instances of sidecars and JPEGs getting updated though I was sure I hadn't changed anything, but when I put the files under the microscope, I discovered there were innocent explanations: I had accidentally changed the caption of a batch of photos instead of just one photo, I had renamed a parent keyword whose child keywords were assigned to the phots, that sort of thing.

But I agree with Johan in general: LR's handling of metadata status isn't the most reliable. Adobe hasn't paid much attention to these issues over the years, partly because, without a reproducible case or a clear pattern of behavior, the engineers throw up their hands and say "nothing we can do". And making a reproducible test case in these situations appears very difficult.

If you're interested in pursuing this, the next time you notice a mysterious update, immediately go to your backups and see if you have a previous version. If you do, upload both versions to Dropbox or similar and post the sharing link here, and I can see if there are any significant metadata changes or other evidence of something that might have confused LR. And then maybe post an actionable bug report...

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Report · Jun 15, 2020

> I discovered there were innocent explanations: I had accidentally changed the caption of a batch of photos instead of just one photo, I had renamed a parent keyword whose child keywords were assigned to the phots, that sort of thing.

I'm certain that's not the case here - I've had it happen literally by doing nothing other than launching & quitting Lightroom. I opened it, gotten a phone call, quit (not having done anything at all), then some random files had changed. Because I've observed it happening so unpredictably, I've made a habit of *always* running a backup task - which presents a summary of diffs before copying - every time immediately after using LR. And even the case above I've ound it modifying some random photos.

>>upload both versions to Dropbox or similar and post the sharing link here

You mean just post the jpg file from before & after the LR unnecessary write?

>>immediately go to your backups and see if you have a previous version

I absolutely do. Every time LR does this, I go back & restore the correct backed-up versions, since I'm not especially interested in LR overwriting images with unknown/unrequested changes.

Report · Jun 15, 2020

"You mean just post the jpg file from before & after the LR unnecessary write?"

Right. I can do a detailed comparison of the low-level metadata fields before and after.

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Report · Jun 15, 2020

Here you go: https://metal450.tk:9988/filerun/wl/?id=4wKMhHKOwur0viXT5xCdDQD1wHz5QvPr

Report · Jun 15, 2020

Sorry I didn't read all of your post before I made my first reply.

So you store you images on a NAS (networked device of some type), is that correct?

Could be the NAS is modifying the files in some way.

I have always used the Auto Write changes to XMP since I started using LR 12+ years ago and I have never had LR randomly write to the xmp files.

Just how do you know it is LR that is making changes to the XMP files?

Report · Jun 16, 2020

> So you store you images on a NAS (networked device of some type), is that correct?

No, I don't store them on a NAS.

> making changes to the XMP files?

Making changes to jpgs, not XMP, as described.

> Just how do you know it is LR that is making changes

Also clearly described in multiple posts - i.e.: I've had it happen literally by doing nothing other than launching & quitting Lightroom. I opened it, gotten a phone call, quit (not having done anything at all), then some random files had changed. Because I've observed it happening so unpredictably, I've made a habit of *always* running a backup task - which presents a summary of diffs before copying - every time immediately after using LR. And even the case above I've ound it modifying some random photos.

Report · Jun 15, 2020

I've identified one possible cause of the issue. The file before.jpg has these altitude fields:

[EXIF]          GPS Altitude Ref                : Above Sea Level
[EXIF]          GPS Altitude                    : 77.72 m

while after.jpg has just one field:

[EXIF]          GPS Altitude                    : 50 m

That has the wrong altitude and doesn't even contain the GPS Altitude Ref field as required by the standard.

I believe LR 7.3, 7.4, or 7.5 introduced some bugs with GPS Altitude, which weren't fixed until LR 8.1:

https://feedback.photoshop.com/photoshop_family/topics/lightroom-address-lookup-overwrites-existing-...

I think what may be happening is that LR imported the photo with the wrong altitude, and then metadata-comparison logic compares that incorrect in-catalog altitude with the correct value on disk, sees that they are different, and writes the metadata (with the incorrect value from the catalog).

I imported before.jpg into my LR 8.2.1, and the correct altitude displayed in the Metadata panel. LR didn't write the file's metadata automatically. When I manually did Metadata > Save Metadata To File, it wrote the correct altitude fields.

I can't confirm this is the cause of your issue, because Adobe in its wisdom doesn't provide versions earlier than 8.2.1 for download. But updgrading to the latest (9.2.1) will certainly avoid this particular bug with altitude.

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Report · Jun 16, 2020

Just upgraded to 9.2.1, still happens. I've added another pair of Before & After photos to the same link (copied below), this time where changes were written by 9.2.1. Again, all I did was open LR and leave it opened for a few minutes, then quit, then run a diff between my originals & their backups. As usual, it wrote changes to a bunch of jpgs that I did not modify.

https://metal450.tk:9988/filerun/wl/?id=4wKMhHKOwur0viXT5xCdDQD1wHz5QvPr

Report · Jun 16, 2020

I'll take a look this evening.

Report · Jun 16, 2020

I imported the samples, "921 - before.jpg" and "921 - after.jpg", into my LR 9.3 / Mac OS 10.15.5, and the problem didn't occur in my installation with Automatically Write enabled. When I then did a manual Metadata > Save Metatadata To File, I saw a bunch of fields that LR normally adds to the metadata when it saves it.

This suggests the issue is specific to your catalog. You could try creating a new test catalog and importing a few photos into it. If the problem doesn't occur with that new catalog, that would confirm that the issue is with your particular catalog.

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Report · Jun 16, 2020

The jpgs were just provided as Before+After samples for the sake of comparing metadata, as you had requested - I wouldn't expect it to happen with yours, because as discussed, the problem isn't consistent or always replicatable. That particular "before" image has been in my catalog since it was taken, years ago. It wasn't until just now that Lightroom decideed to write changes to it (when no changes have been made). Next time, it may not write to any images. It may not do it all week. Next week, it may write over a hundred of them. It's random. So even if I create a new test catalog and add a few test photos, if it doesn't exhibit the bug, that doesn't really tell us anything.

Again, I was just providing those for the purpose of diffing the metadata, as you requested.