P: Panorama Photo Merge not working (Windows - with Custom Scale Factor)

Thanks. The next thing I can think of that might shed more light on what the root problem is is slightly involved. From https://forums.adobe.com/thread/925598, this should work for Lightroom Desktop as well:

To get Lightroom traceback info:

 

Windows 
1. Right click the Lightroom icon you use to launch on the desktop and choose Copy from the menu. 
2. Right click the Desktop and choose Paste from the menu. 
3. Right click the new icon and choose Properties... from the menu. 
4. In the Target field of the properties dialog append -tracebacks (separated from the path by a space): 
(It will look like this at the end when you're done (leave the rest of the path alone): lightroom.exe" -tracebacks) 
5. In the general tab, you might also want to change the name so you can easily visually distinguish this new icon from the original (we'll delete it when we're done). 
6. Go to this site in your browser: https://docs.microsoft.com/en-us/sysinternals/downloads/debugview
7. On the right hand side of the page, click the "Run DebugView" link (it's safe – it's just a debug output viewer from Microsoft) 
8. Click through the Eula if necessary. 
9. With DebugView running, double click the new icon we created in steps 1-5. 
10. Repeat the steps in Lightroom that cause the error message or hang that you are seeing. 
11. Save the output. You can either highlight and copy/paste or choose "Save as..." from the menu to save the output to a file.
 
Mac 
1. In Finder, navigate to the Utilities subfolder of the Applications folder (Command + Shift + U). 
2. Double Click Terminal.app 
3. Paste the following text: '/Applications/Adobe Lightroom 3.app/Contents/MacOS/Adobe Lightroom 3' -tracebacks 
(Note that this may be different for some versions of LR, like RC/Beta releases, etc) 
4. Press enter to start. 
5. Repeat the steps in Lightroom that cause the error message or hang that you are seeing. 
6. Use the Shell -> Export Text As... menu item (Command + S) to save the output to a file (or select it for copy and paste).
 
Note that the output this produces requires the exact build number of LR that emitted it to be translated into a stack trace with source file names and line numbers.

I was running lightroom classic version 8.3.1. Classic does merge them successfully and pretty quickly I should add. 

Which version of Lightroom Classic were you using when you successfully merged the images? I'm curious if Lightroom Classic 8.3 merges this image set successfully.

I did as you said and it didn't change the result. The progress always stops at 0% of creating the preview (it does not seem to start at all), I assume it's not actually processing the preview as the CPU usage drops to 0% after a couple of seconds of starting and stays there.

Carlos, can you put the source images into an album, then choose 'Store Album Locally' for that album in the 3-dot menu in the grid header bar (when the album is selected)?

After that is done, the album should have a blue dot on it in the left side panel:



You'll see a dialog that informs you how much disk space will be consumed by the originals locally.

The idea with this is to establish whether the problem has to do with source file access during the merge operation.

Also, does the progress bar stop at the same percentage each time? If so, what percentage? If not, what's an example value that you've seen?

Thanks

Got it. Thanks!

I have sent the diagnostic log document to the adress.

Next step Carlos will be to perform the following:

1. Close Lightroom.
2. Restart the computer.
3. Open Lightroom.
4. Attempt the merge
5. When it fails, go to Preferences>Account and hold down the [A/t/Opt] Key and click the [Diagnostic Log] button.  

Send the log to me at:

I am using the spherical projection as well, but boundary warp set to 0 (setting it to 100 makes no difference). I have just updated to windows version 1903, but that hasn't fixed the issue either.

Ok. My first test was on Mac. I just tried the merge on a Windows laptop Win 10 (1809) and it merged fine within 90 seconds. 

Your free space on your hard drives looks fine so no issue there. Your Windows version is a little older and you might check Microsoft for an update. 

When I did the merge, I was using a Spherical Projection and had Boundary Warp set to 100.  What are your settings there?