HDR merge stopped working - error message 'unknown error occurred'

[Joanne_Charnwood]

I use Ctrl+shift+H to stack and merge bracketed frames in light room. Meaning I can set up a string of merge jobs and they all run the in background - perfect. This has worked for me until yesterday. Now nothing will merge - I just get the error message 'unknown error occurred'. Started on Friday night.

Have tried many bracket sets (all taken on tripod so well aligned) - all fail and give me that message.

Also took some of the failed brackets and did the hdr merge the long way in photoshop - that works fine.

I have 100's of these to do.....

The last time my merge worked was early on Friday evening when I used the Ctrl+shift+M - to merge some focus stacked brackets.

Cache just cleared - Video driver updated and nothing to roll back.....still not working.....

Does anyone else have the same experience ?

Or did anyone already have this problem and work out a solution?

[johnrellis]

Make sure you have at least tens of gigabytes free on the drive containing the photos and on the main Windows drive (usually C).  Merge creates temporary files on the C drive that can be quite large.

[Joanne_Charnwood · Accepted solution]

Thank you JohnRellis,.

It turned out that when I reset the Lightroom properties the problem went away, Still not sure what casued it but at least I can work again.

[johnrellis]

Glad you got it resolved.  The LR preferences implementation has a serious flaw, and resetting preferences fixes a large number of mysterious problems.