My guess is that Photoshop is updating some EXIF data fields in the raw file, for example the "edited with software" field. Since Lightroom probably has already set that field, it gives you a warning that something changed.
Alternatively to what you are doing (export then open in PS), you can use the LR command "edit in Photoshop" and LR will do the needed things with passing files back and forth with Photoshop. (LR creates a new PSD file, adds it to the catalog, and tells PS to edit that file and not the original.)
Users have complained for years about spurious metadata-has-changed notifications. If you're confident that you're not editing the file itself outside of LR, then choosing Overwrite Settings will rewrite the metadata in the file with the catalog metadata and (usually) make the spurious notification go away.
Unfortunately, LR doesn't tell you which metadata fields have changed, so users are left flying blind. I believe Rob Cole had a plugin that would tell you metadata differences between the catalog and the disk file, but his Web site has been down for a couple of weeks now.
ManiacJoe: My guess is that Photoshop is updating some EXIF data fields in the raw file, for example the "edited with software" field. Since Lightroom probably has already set that field, it gives you a warning that something changed.
Interesting hypothesis. I just tested that with LR 5.7.1, Photoshop CC 2014, OS X 10.10 and couldn't reproduce the problem. I exported a TIFF from a cataloged raw file into the same folder as the raw, edited the TIFF and changed some of its metadata in Photoshop, and saved it. LR didn't report a metadata-has-changed notification.
In general, I'd be (only moderately) surprised that if you edited x.tif in PS, it would change any metadata in x.cr2 or x.xmp.
I've had this message crop up more times than I care to remember, and like yourself, I never edited, or even opened a file outside of LR... never got to the root of it!
Just taken a look (since reading this thread) at some old pics in LR - there's dozens of jpegs with the dreaded !, intriguingly, from entire sessions - none of which have been opened outside of LR! There are also a few isolated NEFs with the same "Metadata has confllict" message.
The LR crew really ought to take a look at this, the first few times of getting this message can be very unnerving.
Thanks for the answer, Joe - it might be the case, but I haven't done a thing to some of the files that are showing a 'changed' status.
Thanks, John, that's what I've been mostly doing, when I'm confident that I haven't done anything to the outside of LR, but it is a bit nervewracking. I agree with our KevetS that LR should be taking a look at why this is happening to so many and so often. But I'll sleep easier now, and won't worry about it too much. thanks ALL for your replies!
I have this problem and it is driving me crazy as it appears constantly on every single image file. I edit hundreds of images on a regular basis and the thumbnails in the Develop module already show more than enough information as it is. This used to be just an occasional occurrence, but now this invitation to overwrite metadata never goes away.
All my images are stored on a network attached Win Home Server 2011 and the catalogue is on one of my internal 3Tb drives (E) on the "local" machine. It used to be on an M.2 SSD 256Gb (C) drive and if I remember correctly, the notification problem started very soon after an LR update and/or moving the catalogue.
I have about 40,000 images and every single one in LR CC 2015 displays this message.
PC with Win 10 Pro, 32 Gb RAM, Intel i7 6 core, M.2 SSD 256Gb (C) drive, 2x 3Tb WD Black, Images stored on WHS 2011 via local network
This prompted me to move & set the LR catalogue location back in "Pictures" on the original (C) drive, but the problem is no different. When working in Lightroom CC (2015.6 release) exclusively i.e.no other image editing program running, the arrows start to reappear.
I've tried "Overwrite Settings with those from the catalogue" and then "Photo/Read metadata from file" but to no avail.
Please Adobe, get someone from the company to sort this out
I agree, Woofy - there should be some clear answer to this problem. My issue seems to have gone away - I get it very sporadically and infrequently now, without having done anything, really - except go to the CC version. I wish I could help you more but I have no real answer - John above at least helped me know what to do when it appeared but if you are getting it on every image or just about every one, that's not the correct answer for you. good luck!
I can't believe Adobe still haven't done anything to address this issue.
I saw comments on one of their blog posts from back in 2013 where people were saying "At least show us a side by side comparison of what metadata has changed, so we can make an informed decision!" ...but still we just get a dialogue box which is the equivalent of someone with their arms behind their back asking you to 'pick a hand'.
This is primarily a user-to-user forum in which Adobe product developers rarely participate. Adobe wants product feedback posted on the official feedback forum: http://feedback.photoshop.com/photoshop_family/products/photoshop_family_photoshop_lightro om . They do read every post there, and sometimes reply. That forum has a number of topics about spurious metadata conflicts that are pretty old (2012 and earlier), and they seem to concern bugs that were fixed long ago. I don't see any recent topics about the issue.
If you post there, be sure to include as much detail as you can about your issue, including your exact version of LR (Help > System Info) and version of Mac or Windows, and any recipes for reproducing the problem (if possible). Simply linking to another thread will likely get your post ignored by Adobe.