Issue using Remote Desktop Manager mRemoteNG and its freeware alternatives

Question

I use Remote Desktop Manager i.e mRemoteNG which stopped working on my Windows and does not work despite reinstallation and other fixes.

While I would like to know freeware / opensource alternatives to mRemoteNG which i can use for RDP and SSH connection below is elaboration of my issue.

I used to connect to Windows and Linux hosts and organize my server list using mRemoteNG.

Below is the Current Error launching mRemoteNG and it crashes right after it starts.

An item with the same key has already been added.

at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
   at mRemoteNG.App.Update.UpdateFile.FromString(String content)
   at mRemoteNG.App.Update.UpdateFile..ctor(String content)
   at mRemoteNG.App.Update.UpdateInfo.FromString(String input)
   at mRemoteNG.App.Update.AppUpdater.GetUpdateInfo()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

OS: Microsoft Windows NT 10.0.19045.0
mRemoteNG Version: 1.77.1.27713
Edition: Portable
Cmd line args: 

I tried deleting the confCons.xml and the <user_home>/Appdata/Local and Roaming folders for mRemoteNG and launching the software.

The same software when copied to another Windows host works fine.

Kindly suggest.