Hi Folks,
I'd appreciate any help with the following query.
Every time I add new metadata to an image (keywords etc), an exclamation mark symbol appears in the top right hand corner of the thumbnail 'frame'. The error message states that "The metadata for this photo has been changed by another application. How should LR synchronise the data?".
Any ideas as to why this is happening and what it means?
Thanks for any input,
Regards
Stephen Edgar

I'd like to know the answer to this question as well. It seems to keep cropping up with jpg images in my catalogue.

You probably don't have "Automatically write XMP metadata" on for one. Are you working with the images in Bridge too? Or some application that might be updating the metadata outside of LR? There's a mismatch, and that's why you see the symbol, not a big deal. Since you just updated something, chances are, you want the over-ride the older metdata so you want to sync it with the newer data (or you can turn on the Auto write XMP but that may slow the show things down).

True, I do not have "Automatically write..." checked. I can try that. The thing is, I don't really use any other application to alter the metadata. I do start up Bridge occasionally, but it would have to be altering the data without my knowledge.

When Bridge renders images it can indeed alter the metadata, depending on your preferences, which may cause the issue seen.
Autowrite since version 1.3 is fine, not having it enabled will definitely cause problems with Bridge syncronisation and it also means if LR database corrupts for any reason, you lose all your edits. I always Auto write changes to safegaurd my data.