AW: EXT: VNC connection freezes immediately on version 1.6.0 when connecting to Windows Server 2022 PCs

["Timpl, Markus" <ma...@primetals.com>]

I had the same issue with UltraVNC. The solution for me was to set “disable-display-resize”.


Von: Nicholas Partlin <Ni...@tomago.com.au>
Gesendet: Mittwoch, 26. November 2025 03:43
An: user@guacamole.apache.org
Betreff: EXT: VNC connection freezes immediately on version 1.6.0 when connecting to Windows Server 2022 PCs

Sie erhalten nicht häufig E-Mails von nicholas.partlin@tomago.com.au<ma...@tomago.com.au>. Erfahren Sie, warum dies wichtig ist<https://aka.ms/LearnAboutSenderIdentification>
EXTERNAL SENDER
Caution: This email originated from outside of Primetals Technologies. Please be cautious when clicking links or opening attachments. Never enter username and password unless having verified the source!

In Guacamole 1.6.0 I’ve found some VNC connections seem to freeze immediately. Essentially it stays stuck as a “screenshot” of when I first opened the connection. The connection is still open, and I can still interact (i.e. if I move a window in the Guacamole connection I can see it has an effect by monitoring the physical screen or watching it through another remote software, but nothing appears to change in Guacamole).

OS affected: So far have only observed this issue with VNC connections to Windows Server 2022. Other versions of Windows appear to be fine.
Guacamole Versions affected: Testing on 1.6.0 in a docker stack. Also tested with an older version of Guacamole (1.5.4, native install) which works fine with the same connections.
LibVNC: The libvnc version in the guacd container (in /opt/guacamole/lib) is 0.9.15, I tested replacing this with 0.9.14 but the issue persisted.
VNC Server: Using the latest version of UltraVNC server (1.6.4.0), however the issue is the same on older versions too. Tested with/without MSLogon II enabled, no difference. Also tested with TightVNC server which does NOT present the same issue.
I also tested the connections with TightVNC Viewer and Remmina, both of which had no problems.
Nicholas Partlin
​​​​
Graduate ‑ IT & Automation
638 Tomago Road, Tomago, NSW 2322
E Nicholas.Partlin@tomago.com.au<ma...@tomago.com.au>
|
www.tomago.com.au<http://www.tomago.com.au/>
<https://www.tomago.com.au/>
[cid:image001.jpg@01DC62A2.8B72E8E0]<https://www.tomago.com.au/>
We acknowledge that we live and work on the land of the Worimi people, owners of the land on which we operate.
​We pay our respects to Elders past, present and emerging and celebrate the diversity of Aboriginal peoples and their ongoing cultures and connections to the lands and waters of NSW.
This transmission is confidential and intended for the addressee only. If you have received it in error, please delete it and notify the sender. Unless explicitly attributed, the opinions expressed in this E-mail are those of the author only and do not represent the official view of Tomago Aluminium Company Pty Limited. Tomago Aluminium Company Pty Limited checks all inbound/outbound e-mail for Viruses. However, we advise that this e-mail and any attached files should be re-scanned to detect viruses. Tomago Aluminium Company Pty Limited accepts no liability for loss or damage (whether caused by negligence or not) resulting from the use of this or any attached files.

RE: EXT: VNC connection freezes immediately on version 1.6.0 when connecting to Windows Server 2022 PCs

[Nicholas Partlin <Ni...@tomago.com.au>]

Thanks Markus!

Setting disable-display-resize as true (AKA ticking “Disable resize of remote display” checkbox in the connection parameters) solved the problem for me too.

Cheers,
Nick

Nicholas Partlin
Graduate - IT & Automation
638 Tomago Road, Tomago, NSW 2322
E Nicholas.Partlin@tomago.com.au|www.tomago.com.au
We acknowledge that we live and work on the land of the Worimi people, owners of the land on which we operate. 
​We pay our respects to Elders past, present and emerging and celebrate the diversity of Aboriginal peoples and their ongoing cultures and connections to the lands and waters of NSW.
This transmission is confidential and intended for the addressee only. If you have received it in error, please delete it and notify the sender. Unless explicitly attributed, the opinions expressed in this E-mail are those of the author only and do not represent the official view of Tomago Aluminium Company Pty Limited. Tomago Aluminium Company Pty Limited checks all inbound/outbound e-mail for Viruses. However, we advise that this e-mail and any attached files should be re-scanned to detect viruses. Tomago Aluminium Company Pty Limited accepts no liability for loss or damage (whether caused by negligence or not) resulting from the use of this or any attached files.