David Sparer edited this page Mar 20, 2018 · 13 revisions

This page is meant to be a collection of common questions, odd quirks, and known issues that you may experience when using mRemoteNG.

If your question is not covered here, you can also check the following places:

Table of Contents

  1. I can't open more than X number of RDP sessions. New sessions fail with error code 3334
  2. RDP connections fail with error code 264
  3. ATI Tray Tools
  4. mRemoteNG crashes with the error "Class not registered" when trying to connect using RDP
  5. VNC connections fail with the error "The server is using an unsupported version of the RFB protocol. The server is using version 4.1 but only version 3.x is supported."
  6. Cannot click some UI elements in an RDP connection window
  7. SSH login fails when password contains extended ASCII characters
  8. RDP Reconnects whenever I resize the window

I can't open more than X number of RDP sessions. New sessions fail with error code 3334

The issue here is likely the amount of resources available to the RDP component to open the connection. This was alleviated in MR-714 and MR-864.

Other things you can do to help reduce the issue:

  • On your RDP connections, set CacheBitmaps to False (this reduces the memory usage of each connection)
  • Consider removing KB2830477 if you have it installed. This seems to increase the likelyhood of getting 3334 error codes.

RDP connections fail with error code 264

This issue is often caused by trying to retrieve session information.

Try doing the following:

  • Disable "Automatically get session information" (Tools -> Options -> Advanced)

ATI Tray Tools

mRemoteNG is not compatible with ATI Tray Tools. We are aware of the issue and hope to have it fixed in a future version. We recommend that you disable or uninstall ATI Tray Tools while using mRemoteNG.


mRemoteNG crashes with the error "Class not registered" when trying to connect using RDP

You may also see a message like "System.Runtime.InteropServices.COMException (0x80040154)"

If you are running mRemoteNG on Windows 7 or Server 2008:

  • You may be missing one or more required windows updates (see the page on Prerequisites).
  • A common issue is that KB2574819 is either missing or has been installed after KB2592687. They must be installed in the correct order. If you do not have KB2574819, follow these instructions:

If you are running mRemoteNG on Windows 8/10 or Server 2012+:

  • Try to repair the mRemoteNG installation using the installer or uninstall/reinstall. Receiving this error on these OS's is just an install fluke (or you've fiddled with your registry).

VNC connections fail with the error "The server is using an unsupported version of the RFB protocol. The server is using version 4.1 but only version 3.x is supported."

RFB version 4.0 and higher is a proprietary version owned by RealVNC Limited. Building support for newer versions will likely result in licensing fees. Therefore, it is unlikely that mRemoteNG will have support for version 4.0+ anytime soon.

Unfortunately, the only way around this limitation is to use an open source implementation of VNC server such as TightVNC or UltraVNC


Cannot click some UI elements in an RDP connection window.

It may seem like some elements are not clickable along the top and left sides of your RDP connection window. More information can be found in issue #210

This is likely due to non-standard (>100%) DPI scaling on your local machine.

To turn this off:

On Windows 7 / 8

  • Start menu -> Control Panel -> Display
  • Ensure the option Smaller - 100% (default) is selected

On Windows 10

  • Start menu -> Settings -> Display
  • Ensure the slider under Change the size of text, apps, and other items is all the way to the left (at 100%)

SSH login fails when password contains extended ASCII characters

Initial login to SSH (or WinSCP) fails when the password contains extended ASCII characters (such as: €šœ£ÁØë). Typing the password into the SSH session directly works.

Investigation suggests that there is an issue in character encoding when mRemoteNG passes the value to the cmd line, which then invokes PuTTY. This was investigated in issue #186

The only resolution for this issue is to not use extended ASCII characters in passwords that will be sent to PuTTY or similar tools.

RDP tries to reconnect whenever I resize the window

Your RDP connection reconnects after resizing mRemoteNG or the connection panel.

This will occur anytime the connection window changes size and the following connection options are set:

  • Resolution: Fit to Panel
  • Automatic Resize: Yes

To prevent reconnecting, you can do one of several things:

  • Change the resolution to Smart Size. This will scale the original connection area when the view window size changes. This does not preserve aspect ratio.
  • Turn off Automatic Resize. When the view window size changes, you will see scroll bars or dead space.

There is no way to update the view window size without a reconnect. This is an RDP protocol limitation.

You can’t perform that action at this time.
You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. Reload to refresh your session.
Press h to open a hovercard with more details.