Crash when opening any session – RDM 2025.2.13.1 + .NET 9.0.5

Hi,

Can you tell me your exact version of Windows with the build version, as shown by the winver command?

You can also extract file version information from the RDP ActiveX:

(Get-Item "C:\Windows\System32\mstscax.dll").VersionInfo.FileVersion

Best regards,

Hi Marc,
Version 24H2 (OS Build 26100.4202).
Thanks!

Hi,

Isn't this a preview build? Those tend to break frequently and we can't really support them beyond best-effort. Most of the time, when Microsoft breaks the RDP ActiveX in a preview build, the regression never makes it to a stable build: https://support.microsoft.com/en-us/topic/may-28-2025-kb5058499-os-build-26100-4202-preview-d4c2f1ee-8138-4038-b705-546945076f92

do as i do, get back to version Setup.RemoteDesktopManager.2025.1.29.0 and all is working.
dont listen to the excuses of preview windows builds and stuff.

Hi,

Can you try disabling RDP API hooking in RDM and see if the problem goes away? https://docs.devolutions.net/rdm/kb/troubleshooting-articles/rdp-session-troubleshooting/#disable-rdp-api-hooking

I've worked on a fix in MsRdpEx last week. Long story short an internal vtable has changed in preview builds. Older versions of MsRdpEx had it wrong, but didn't do much with the incorrect calls. I added logging of a value which made it crash on versions of Windows that got the vtable wrong (again, only in preview builds). I found a way to properly detect the vtable version, and got that fixed, but every time it's a bit of a cat and mouse game when it comes to insider preview builds. It's not an excuse, it really takes a lot of effort to support them. Some times it's something we can fix on our side, but too often it leads to costly investigations for temporary bugs that we have no control over.

If disabling RDP API hooking works around it, then updating MsRdpEx in the next build of RDM will likely resolve the issue.

Best regards,

Hi,

Can you try disabling RDP API hooking in RDM and see if the problem goes away? https://docs.devolutions.net/rdm/kb/troubleshooting-articles/rdp-session-troubleshooting/#disable-rdp-api-hooking

I've worked on a fix in MsRdpEx last week. Long story short an internal vtable has changed in preview builds. Older versions of MsRdpEx had it wrong, but didn't do much with the incorrect calls. I added logging of a value which made it crash on versions of Windows that got the vtable wrong (again, only in preview builds). I found a way to properly detect the vtable version, and got that fixed, but every time it's a bit of a cat and mouse game when it comes to insider preview builds. It's not an excuse, it really takes a lot of effort to support them. Some times it's something we can fix on our side, but too often it leads to costly investigations for temporary bugs that we have no control over.

If disabling RDP API hooking works around it, then updating MsRdpEx in the next build of RDM will likely resolve the issue.

Best regards,

@Marc-André Moreau
Hi Marc,
Disabling RDP API hooking worked — I’m now able to connect to sessions without any crashes. Thanks a lot for the suggestion!
Should I keep RDP API hooking disabled until the next update of RDM with the updated MsRdpEx? Or is it safe to re-enable it sooner?
Really appreciate the detailed explanation and the quick help.
Thanks again!