Libreoffice and Webdav behind HAProxy

[Jean-Max Reymond]

Hi,
I have a very strange behavior with LibreOffice and Webdav

I have a tomcat server under Ubuntu 22.04 that presents documents with 
the Webdav protocol.

If my tomcat server is behind apache2, I can open and save a document 
with LibreOffice on Ubuntu 22.04 and MS Office on Mac.

If my tomcat server is behind HAProxy, I can open a document with 
LibreOffice under Ubuntu 22.04 and MS Office on Mac but I can't save it 
with Ubuntu 22.04 while it's OK with MS Office on Mac

The message is "Error while saving the template-CRA2 document: 
impossible to create the object in the directory 
https://cloud.exemple.com/WebDav/NESTOR/jmax" translated from french" 
"Erreur lors de l'enregistrement du document template-CRA2: impossible 
de créer l'objet dans le répertoire 
https://cloud.exemple.com/WebDav/NESTOR/jmax"

I have traces in the tomcat servlet but I didn't notice an error code, 
all PROPFIND return 20x.

I have checked that all Webdav directories on the server have write 
permissions.

How do I know what is causing the Webdav error in Libreoffice?

Thanks for your tips,