I am attempting to create high resolution HDR Tilt-Shift Panoramas with Lightroom's Merge To HDR and Merge To Panorama functions. I have taken multiple images with a tilt-shift lens on a Canon 5Ds. Each finished photograph would be composed from 15 or 21 separate images. I take 5 or 7 photographs, 1 stop apart, from the center position then 5 or 7 from the shift right position and the same from the shift left position. Each set of 5 or 7 is merged to hdr to create one dng file. This process works fine. The resulting 3 hdr images are then merged to panorama which completes successfully. When I switch to the develop module or open the panorama file in camera raw I get a message stating "The file appears to be damaged". I have reproduced this error on different computers. My Lightroom version is the 2015.4 Release and Camera Raw is v9.4. Both computers are running Windows 10. It seems to me that Lightroom is struggling with the large file sizes coming from the 5Ds. Has anyone else experience this issue.
I had the same message developing program using Adobe's DNG SDK.
Every dng image has checksum (fingerprint) calculated from raw data. When I overwrite the raw data without updating fingerprint, the message pops out.
My guess is that the merging software you used didn't update the fingerprint of the merged dng.