Dell Repository Manager bootable ISO export fails

I'm using the Dell Repository Manager (v3.4.9 in that case), to create a smartbootable-ISO for multiple server-platforms we have to provide with fw-updates.

I'm not using the webinterface, DRM is installed inside a container (from ol9.6-slim) and it's entrypoint is a script to start the service, configure a proxy (if needed), update all plugins/catalogs - the last available Enterprise catalog is then used to create a repository with most of our supported systems.

Final task is to create the smartbootiso, but recently this task (drm --deployment-type=smartbootiso --location=/path --repository=reponame) keeps failing. Please note: neither the container-base image nor DRM itself was updated in the last 2 months, still using the same image i used back in Nov. 2025, and everything worked like expected back then.

Here's an example of my workflow (inside the container):

$ drm --list=catalogs|awk '/^Enterprise/ {print $4}'
d1755272-19cd-4fda-a4ce-ddf17d9c8451

$ drm --create --repository=TEST_R65_74 --inputplatformlist="R6515,R740,R740xd" --dupformat="linux" --catalog=d1755272-19cd-4fda-a4ce-ddf17d9c8451

Creating repository TEST_R65_74
Repository with name TEST_R65_74 created successfully.

$ drm --list=rep

Listing Repositories...

Name          Latest version   Size      Last modified date
----          --------------   ----      -------------
TEST_R65_74   1.01             3.99 GB   1/22/26 7:56 A.M

$ drm --deployment-type=smartbootiso --location=/export --repository=TEST_R65_74

Job SmartBootableISO_01/22/2026_07:58:47 is scheduled to run at: Thu Jan 22 07:58:50 UTC 2026
Smart Bootable ISO Deployment job started.
<wait a few seconds>
Smart Bootable ISO Deployment job failed.

I can not find any helpful lines in drmpresentation/service.log, the only thing is the following expection out of error.log:

java.util.ConcurrentModificationException
        at java.base/java.util.HashMap$HashIterator.nextNode(HashMap.java:1605)
        at java.base/java.util.HashMap$ValueIterator.next(HashMap.java:1633)
        at com.dell.drm.deploymenttools.DSUISO.createRepository(DSUISO.java:464)
        at com.dell.drm.deploymenttools.DSUISO.create(DSUISO.java:333)
        at com.dell.drm.deploymenttools.DSUISO.run(DSUISO.java:212)
        at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:572)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
        at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
        at java.base/java.lang.Thread.run(Thread.java:1583)

As I thought it has something todo with my container-environment (tried swapping the container base-image to ubuntu:24.04), I set up an Ubuntu 24.04 VM and installed DRM natively -> same issues.

Please note that exporting a suuiso is still working:

$ drm --deployment-type=suuiso --location=/export --repository=TEST_R65_74

Job SUUISO_01/22/2026_09:17:58 is scheduled to run at: Thu Jan 22 09:18:01 UTC 2026
SUU ISO Deployment job started.
SUU ISO Deployment job completed with warnings.

$ file /export/SUUISO_01_22_2026_091758/SUUImage.iso 
/export/SUUISO_01_22_2026_091758/SUUImage.iso: ISO 9660 CD-ROM filesystem data 'CDROM'

Anyways, I would still prefer the bootable ISO :)

Appreciate your help/feedback!

Best,
Matthias