Inspiring

Answered

Lightroom 15.3 Merge to HDR not working properly

Forum|Forum|2 months ago
April 22, 2026
13 replies
256 views

Merge to HDR in LrC 15.3 is stalling (beach ball) or not responding. I frequently merge HDR images for Real Estate photos and today, after updating to LrC 15.3 I had to Force Quit from LrC multiple times to regain control of LrC. I stacked my bracketed shots and used CTRL+H to merge. LrC did process a couple before stalling. After multiple attempts resulting in Force Closing, I tried using the menu commands, no change. I then uninstalled 15.3 and reinstalled a fresh copy of 15.3 and the HDR problem continued. Finally I uninstalled 15.3 and downgraded to 15.2.1 and the Merge to HDR function worked as expected.

Correct answer John_Gerard

Update - after installing the latest MacOS updates (Tahoe 26.5) I re-installed LrC 15.3 and the HDR process is working as expected. I no longer have any issues processing stacks of HDR images.

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johnrellis

Legend

I was also able to stack and merge the sample photos on my LR 15.3 / Mac OS 26.2 / Macbook Pro M2 Max 64 GB. While it’s possible that you’re on Mac OS 26.3.1, which is the cause of the issue (e.g. a different GPU driver), that seems unlikely. It seems more likely there’s something specific to your installation.

Ian Lyons

Community Expert

Fwiw, I’m using macOS 26.4.1

I’ve also checked HDR Merge behaviour on my MacBook Pro M4 Max and Studio Ultra M3. Again, no issues.

John_GerardAuthor

Inspiring

I use a Canon EOS R5 shooting in RAW. 3 bracketed shots -2, 0, +2. I also use a DJI Mavic 4 Pro in RAW. 5 bracketed shots. I experienced issues with stacks from both cameras. I’m shooting for real estate and this process has worked extremely well for years using the same canon camera and my previous DJI Air3 drone. My typical workflow is to import all images from both cameras, auto-stack by time, verify the stacks, Select all stacks and hit CMD+H to allow LrC to process all of the images to HDR. It generally take 20-30 minutes. This was a smaller job and as I ran into issues I started selecting only a single stack, then opening the stack and selecting the individual images. I even tried to open in Photoshop and Merge to HDR (from the menu) but LrC still stalled on that, very different, workflow.

With LrC 15.2.1 reinstalled I started with single stacks but finished up by selecting all remaining stacks, about 8, and all HDR images were processed and stacked as expected.

johnrellis

Legend

If you upload a stack of sample photos that don’t merge, we can see if the issue is a general problem with LR 15.3 or something specific to your installation. You may be able to attach the photos to your reply, but if the forum complains, upload them to Wetransfer, Dropbox, Google Drive or similar free service and post the sharing link here.

John_GerardAuthor

Inspiring

Ok, I uploaded multiple sets from the camera and three sets from the drone to a folder on Google Drive. I set the permissions to “Anyone with the Link” so you should be able to download all of the original RAW files.

I auto-stack by time using 5 seconds as the interval and they should all jump into stacks of proper brackets. Remember, the drone uses 5 brackets for each shot.

Link to HDR Brackets

Standard Link: https://drive.google.com/drive/folders/1jfAZms-QFzVDyzsfEWrot6DPSXLZSiBv?usp=share_link

johnrellis

Legend

Please do the LR menu command Help > System Info and copy/paste the entire contents here so we can see exactly which versions of hardware and software LR thinks you're running and important LR options that are set.

John_GerardAuthor

Inspiring

Lightroom Classic version: 15.2.1 [ 202603161217-0bf813d9 ]
License: Creative Cloud
Language setting: en-US
Operating system: Mac OS 26
Version: 26.3.1 [25D2128]
Application architecture: arm64
Logical processor count: 12
Processor speed: NA
SqLite Version: 3.36.0
Adobe GSDK Version: 1.4.0.212

Power Source: Plugged In, 80%
Built-in memory: 65,536.0 MB
Dedicated GPU memory used by Lightroom: 201.0MB / 53,084.1MB (0%)
Real memory available to Lightroom: 65,536.0 MB
Real memory used by Lightroom: 1,227.7 MB (1.8%)
Virtual memory used by Lightroom: 435,531.9 MB
Memory cache size: 15.7MB
Internal Camera Raw version: 18.2.2 [ 2512 ]
Maximum thread count used by Camera Raw: 5
Camera Raw SIMD optimization: SSE2
Camera Raw virtual memory: 0MB / 32767MB (0%)
Camera Raw real memory: 2MB / 65536MB (0%)

Cache1:
NT- RAM:0.0MB, VRAM:0.0MB, Combined:0.0MB

Cache2:
m:15.7MB, n:0.0MB

U-main: 102.0MB

Standard Preview Size: 6016 pixels
Displays: 1) 6016x3384

Graphics Processor Info:
Metal: Apple M2 Max
Init State: GPU for Export supported by default
User Preference: Auto
Enable HDR in Library: ON
GPU for Preview Generation: Auto (S5_51)

Application folder: /Applications/Adobe Lightroom Classic
Library Path: /Users/johngerard/LrC CAT-Previews-Backups/JohnGerardPhotography.lrcat
Settings Folder: /Users/johngerard/Library/Application Support/Adobe/Lightroom

Installed Plugins:
1) AdobeStock
2) Any Vision
3) ColorChecker Camera Calibration
4) Epson Print Layout
5) ON1 Effects 2023
6) ON1 NoNoise AI 2024
7) ON1 Portrait AI 2022
8) Topaz Photo AI

Config.lua flags:

Ian Lyons

Community Expert

Can you also advise which camera/model that you’re using along with how many files used in each merge.

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