Unable to apply custom template - version mismatch?

Hi,

I wanted to apply a custom template to my custom Collabora Online installation. AFAIK a custom template needed to be created by Collabora Office, since there is no way to create a template by Collabora Online - please correct me if I’m wrong.

Today I installed Collabora Office on my Windows machine - which came as 24.04.15.3.
~10 days back I installed Collabora Online on my AWS EC2 instance - which came as 25.04.3.1-1.

Today I created a template file using Collabora Office and tried to apply it by setting TemplateSource in the CheckFileInfo request. This failed and I found these errors in the CODE log:

Jul 14 10:39:54 code-dev coolwsd[210267]: wsd-210267-210280 2025-07-14 10:39:54.867165 +0000 [ websrv_poll ] WRN  Client - server version mismatch, disabling browser cache. Expected: e724e42045; Actual URI path with version hash: /browser/dist/cool.html| wsd/FileServer.cpp:913
Jul 14 10:39:54 code-dev coolwsd[210267]: wsd-210267-210280 2025-07-14 10:39:54.969847 +0000 [ websrv_poll ] ERR  FileServerRequestHandler: File not found: Invalid URI request (hash): [/browser/e724e42045/branding.js].| wsd/FileServer.cpp:1173
Jul 14 10:39:55 code-dev coolwsd[210267]: wsd-210267-210280 2025-07-14 10:39:55.003789 +0000 [ websrv_poll ] ERR  FileServerRequestHandler: File not found: Invalid URI request (hash): [/browser/e724e42045/branding.css].| wsd/FileServer.cpp:1173
Jul 14 10:39:55 code-dev coolwsd[210267]: wsd-210267-210280 2025-07-14 10:39:55.121474 +0000 [ websrv_poll ] ERR  FileServerRequestHandler: File not found: Invalid URI request (hash): [/browser/e724e42045/branding-desktop.css].| wsd/FileServer.cpp:1173
Jul 14 10:40:05 code-dev coolwsd[212898]: kit-212898-212898 2025-07-14 10:40:05.451093 +0000 [ kitbroker_01e ] ERR  ToMaster-2f6: Failed to save template [file:///tmp/user/docs/MQaUvHvpQ0OJ2vhy/sss]| kit/ChildSession.cpp:1001

This suggests a version mismatch where supposedly the version of the template file does not match the CODE server version.
Next I tried to ‘downgrade’ my CODE installation but found that there actually is no 24.04.15.3 version available and dnf install -y coolwsd-24.04.15.3 failed.

How could I create a custom template file for my custom Collabora Online installation?
How could I match the Collabora Online and Collabora Office versions?

Any pointer or hint would be highly appreciated. Thanks in advance