hi,
I encounter this error when trying to establish an SSH connection to remote Windows hosts.
Here are the details of the errors:
ArgumentOutOfRangeException - Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index') at System.Collections.Generic.List`1.get_Item(Int32 index) at Devolutions.Protocols.Core.MutableLargeArray`1.get_Item(Int32 i) at Devolutions.Protocols.Core.TerminalBuffer.GetAttribute(Int32 ai) at Devolutions.Protocols.SyntaxColoring.SearchLine(TerminalBuffer buffer, Index start, Index end) at Devolutions.Protocols.Xterm.ApplySyntaxColoring(Index index) at Devolutions.Protocols.Xterm.FillScreen(Int32 newDataRow) at Devolutions.Protocols.Xterm.ActualizeData() at Devolutions.Protocols.Xterm.OnNewData() at Devolutions.Protocols.XtermSsh.OnCallback(Callback args) at Devolutions.Protocols.Core.Upper.<>c__DisplayClass35_0.<Post>b__0(Object _) at Avalonia.Threading.SendOrPostCallbackDispatcherOperation.InvokeCore() at Avalonia.Threading.DispatcherOperation.Execute() at Avalonia.Threading.Dispatcher.ExecuteJob(DispatcherOperation job) at Avalonia.Threading.Dispatcher.ExecuteJobsCore(Boolean fromExplicitBackgroundProcessingCallback) at Avalonia.Threading.Dispatcher.Signaled() at Avalonia.Win32.Win32Platform.WndProc(IntPtr hWnd, UInt32 msg, IntPtr wParam, IntPtr lParam) at Windows.Win32.PInvoke.DispatchMessage(MSG* lpMsg) at System.Windows.Forms.Application.LightThreadContext.FPushMessageLoop(msoloop uReason) at System.Windows.Forms.Application.LightThreadContext.RunMessageLoop(msoloop reason, Boolean fullModal) at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(msoloop reason, ApplicationContext context) at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(msoloop reason, ApplicationContext context) at Devolutions.RemoteDesktopManager.Program.Main(String[] args) ------------------------ extended stack ------------------------ at Devolutions.RemoteDesktopManager.Forms.FrmErrorMessage.ShowErrorMessage(ConnectionEngine engine, Exception exception, String message, String title) at Devolutions.RemoteDesktopManager.Forms.FrmErrorMessage.ShowErrorMessage(ConnectionEngine engine, Exception exception, String title) at Devolutions.RemoteDesktopManager.Program.Main(String[] args)
b6284de3-59b1-4fe2-bee5-045cb49299c5.png
Hello,
Thank you for contacting Devolutions support.
Could you please confirm the type of authentication you’re using with your SSH entries? Additionally, is this issue occurring with all entries, or only a specific subset?
To help us investigate further, please send us verbose2 logs. You can follow the steps outlined in the following documentation article to retrieve them:
https://docs.devolutions.net/rdm/kb/how-to-articles/send-ssh-logs-verbose/
Best regards,
Jacob Lafrenière
Hello,
We cannot reproduce this issue as of now. One thing we would like to know is if you are using either the "Automatically open the file transfer tab" option in your SSH entry's properties or the SFTP toggle button in the opened entry?

If you are, could you try without that option and see if the error still happens?
Another thing we would like to know is if you have any syntax highlighting configured on your entry.
Best Regards,
Michaël Beaudin
164e5c08-ba1a-41f7-a941-502e593f3e9c.png
4cef07eb-4e50-4177-a23e-c2d52627872f.png
Hello,
Thank you for contacting Devolutions support.
Could you please confirm the type of authentication you’re using with your SSH entries? Additionally, is this issue occurring with all entries, or only a specific subset?
To help us investigate further, please send us verbose2 logs. You can follow the steps outlined in the following documentation article to retrieve them:
https://docs.devolutions.net/rdm/kb/how-to-articles/send-ssh-logs-verbose/
Best regards,
@Jacob Lafrenière
hello @Jacob Lafrenière
This issue started occurring after I upgraded to version 2025.2, and it affects all my SSH connections when the remote hosts are Windows, not Linux or any other OS. I am using a username and password for authentication.
and here is verbos2 logs
[7/17/2025 7:46:05 PM] Devolutions.ProtocolsSharp: 2025.7.1.1 OS: Windows [7/17/2025 7:46:05 PM] Terminal font: Consolas [Consolas, fixed=True] [7/17/2025 7:46:05 PM] Starting SSH, verbose level: 2 [7/17/2025 7:46:05 PM] Setting up connection [7/17/2025 7:46:05 PM] Connecting to: 172.16.144.2:22 (IPV_ANY) [7/17/2025 7:46:05 PM] SSH version banner: SSH-2.0-OpenSSH_for_Windows_9.5 [7/17/2025 7:46:05 PM] Sending kex init [7/17/2025 7:46:05 PM] Received kex init [7/17/2025 7:46:05 PM] Selected algorithms: curve25519-sha256(strict), ssh-ed25519, chacha20-poly1305@openssh.com, chacha20-poly1305@openssh.com, implicit by cipher, implicit by cipher, none, none [7/17/2025 7:46:05 PM] Sending Ed25519 kex init [7/17/2025 7:46:05 PM] Received Ed25519 kex reply [7/17/2025 7:46:05 PM] Successfully authentified server [7/17/2025 7:46:05 PM] Sending new keys message [7/17/2025 7:46:05 PM] Received new keys message [7/17/2025 7:46:05 PM] Sending userauth service request [7/17/2025 7:46:05 PM] Received extension info message [7/17/2025 7:46:05 PM] Server accepts public key types: ssh-ed25519,sk-ssh-ed25519@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com,ssh-dss,ssh-rsa,rsa-sha2-256,rsa-sha2-512 [7/17/2025 7:46:06 PM] Received service accepted message [7/17/2025 7:46:06 PM] Sending userauth init request [7/17/2025 7:46:06 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:46:06 PM] Starting interactive authentication [7/17/2025 7:46:06 PM] Sending userauth interactive request [7/17/2025 7:46:06 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:46:06 PM] Starting password authentication [7/17/2025 7:46:06 PM] Sending userauth password request [7/17/2025 7:46:06 PM] Received userauth success [7/17/2025 7:46:06 PM] User authenticated successfuly by password [7/17/2025 7:46:06 PM] Sending session channel open request: 0|- [7/17/2025 7:46:06 PM] Received global request: hostkeys-00@openssh.com, no need to reply [7/17/2025 7:46:06 PM] Received channel open confirmation: 0|0 WS 200000|0 MPS 32000|32768 [7/17/2025 7:46:06 PM] Sending pty request: 0|0 xterm-256color, 198x42 [7/17/2025 7:46:06 PM] Received channel success: 0|0 [7/17/2025 7:46:06 PM] Sending environment variable request: LANG=en_US.UTF-8 0|0 [7/17/2025 7:46:07 PM] Received channel failure: 0|0 [7/17/2025 7:46:07 PM] The server did not accept the environment variable [7/17/2025 7:46:07 PM] Sending shell request: 0|0 [7/17/2025 7:46:07 PM] Received channel success: 0|0 [7/17/2025 7:48:26 PM] Devolutions.ProtocolsSharp: 2025.7.1.1 OS: Windows [7/17/2025 7:48:26 PM] Terminal font: Consolas [Consolas, fixed=True] [7/17/2025 7:48:26 PM] Starting SSH, verbose level: 2 [7/17/2025 7:48:26 PM] Setting up connection [7/17/2025 7:48:26 PM] Connecting to: 172.16.144.2:22 (IPV_ANY) [7/17/2025 7:48:26 PM] SSH version banner: SSH-2.0-OpenSSH_for_Windows_9.5 [7/17/2025 7:48:26 PM] Sending kex init [7/17/2025 7:48:26 PM] Received kex init [7/17/2025 7:48:26 PM] Selected algorithms: curve25519-sha256(strict), ssh-ed25519, chacha20-poly1305@openssh.com, chacha20-poly1305@openssh.com, implicit by cipher, implicit by cipher, none, none [7/17/2025 7:48:26 PM] Sending Ed25519 kex init [7/17/2025 7:48:27 PM] Received Ed25519 kex reply [7/17/2025 7:48:27 PM] Successfully authentified server [7/17/2025 7:48:27 PM] Sending new keys message [7/17/2025 7:48:27 PM] Received new keys message [7/17/2025 7:48:27 PM] Sending userauth service request [7/17/2025 7:48:27 PM] Received extension info message [7/17/2025 7:48:27 PM] Server accepts public key types: ssh-ed25519,sk-ssh-ed25519@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com,ssh-dss,ssh-rsa,rsa-sha2-256,rsa-sha2-512 [7/17/2025 7:48:27 PM] Received service accepted message [7/17/2025 7:48:27 PM] Sending userauth init request [7/17/2025 7:48:27 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:48:27 PM] Starting interactive authentication [7/17/2025 7:48:27 PM] Sending userauth interactive request [7/17/2025 7:48:27 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:48:27 PM] Starting password authentication [7/17/2025 7:48:27 PM] Sending userauth password request [7/17/2025 7:48:27 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:48:27 PM] No authentication method available [7/17/2025 7:48:27 PM] Bytes sent: 1496, Bytes received: 1820 [7/17/2025 7:48:27 PM] Packets sent: 7, Packets received: 8 [7/17/2025 7:48:27 PM] Kex completed: 1 [7/17/2025 7:49:34 PM] Devolutions.ProtocolsSharp: 2025.7.1.1 OS: Windows [7/17/2025 7:49:34 PM] Terminal font: Consolas [Consolas, fixed=True] [7/17/2025 7:49:34 PM] Starting SSH, verbose level: 2 [7/17/2025 7:49:34 PM] Setting up connection [7/17/2025 7:49:34 PM] Connecting to: 172.16.144.2:22 (IPV_ANY) [7/17/2025 7:49:34 PM] SSH version banner: SSH-2.0-OpenSSH_for_Windows_9.5 [7/17/2025 7:49:34 PM] Sending kex init [7/17/2025 7:49:34 PM] Received kex init [7/17/2025 7:49:34 PM] Selected algorithms: curve25519-sha256(strict), ssh-ed25519, chacha20-poly1305@openssh.com, chacha20-poly1305@openssh.com, implicit by cipher, implicit by cipher, none, none [7/17/2025 7:49:34 PM] Sending Ed25519 kex init [7/17/2025 7:49:34 PM] Received Ed25519 kex reply [7/17/2025 7:49:34 PM] Successfully authentified server [7/17/2025 7:49:34 PM] Sending new keys message [7/17/2025 7:49:34 PM] Received new keys message [7/17/2025 7:49:34 PM] Sending userauth service request [7/17/2025 7:49:34 PM] Received extension info message [7/17/2025 7:49:34 PM] Server accepts public key types: ssh-ed25519,sk-ssh-ed25519@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com,ssh-dss,ssh-rsa,rsa-sha2-256,rsa-sha2-512 [7/17/2025 7:49:35 PM] Received service accepted message [7/17/2025 7:49:35 PM] Sending userauth init request [7/17/2025 7:49:35 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:49:35 PM] Starting interactive authentication [7/17/2025 7:49:35 PM] Sending userauth interactive request [7/17/2025 7:49:35 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:49:35 PM] Starting password authentication [7/17/2025 7:49:35 PM] Sending userauth password request [7/17/2025 7:49:35 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:49:35 PM] No authentication method available [7/17/2025 7:49:35 PM] Bytes sent: 1496, Bytes received: 1820 [7/17/2025 7:49:35 PM] Packets sent: 7, Packets received: 8 [7/17/2025 7:49:35 PM] Kex completed: 1 [7/17/2025 7:52:34 PM] Devolutions.ProtocolsSharp: 2025.7.1.1 OS: Windows [7/17/2025 7:52:34 PM] Terminal font: Consolas [Consolas, fixed=True] [7/17/2025 7:52:34 PM] Starting SSH, verbose level: 2 [7/17/2025 7:52:34 PM] Setting up connection [7/17/2025 7:52:34 PM] Connecting to: 172.16.144.2:22 (IPV_ANY) [7/17/2025 7:52:34 PM] SSH version banner: SSH-2.0-OpenSSH_for_Windows_9.5 [7/17/2025 7:52:34 PM] Sending kex init [7/17/2025 7:52:34 PM] Received kex init [7/17/2025 7:52:34 PM] Selected algorithms: curve25519-sha256(strict), ssh-ed25519, chacha20-poly1305@openssh.com, chacha20-poly1305@openssh.com, implicit by cipher, implicit by cipher, none, none [7/17/2025 7:52:34 PM] Sending Ed25519 kex init [7/17/2025 7:52:35 PM] Received Ed25519 kex reply [7/17/2025 7:52:35 PM] Successfully authentified server [7/17/2025 7:52:35 PM] Sending new keys message [7/17/2025 7:52:35 PM] Received new keys message [7/17/2025 7:52:35 PM] Sending userauth service request [7/17/2025 7:52:35 PM] Received extension info message [7/17/2025 7:52:35 PM] Server accepts public key types: ssh-ed25519,sk-ssh-ed25519@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com,ssh-dss,ssh-rsa,rsa-sha2-256,rsa-sha2-512 [7/17/2025 7:52:35 PM] Received service accepted message [7/17/2025 7:52:35 PM] Sending userauth init request [7/17/2025 7:52:35 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:52:35 PM] Starting interactive authentication [7/17/2025 7:52:35 PM] Sending userauth interactive request [7/17/2025 7:52:35 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:52:35 PM] Starting password authentication [7/17/2025 7:52:35 PM] Sending userauth password request [7/17/2025 7:52:35 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:52:35 PM] No authentication method available [7/17/2025 7:52:35 PM] Bytes sent: 1496, Bytes received: 1820 [7/17/2025 7:52:35 PM] Packets sent: 7, Packets received: 8 [7/17/2025 7:52:35 PM] Kex completed: 1 [7/17/2025 7:53:10 PM] Devolutions.ProtocolsSharp: 2025.7.1.1 OS: Windows [7/17/2025 7:53:10 PM] Terminal font: Consolas [Consolas, fixed=True] [7/17/2025 7:53:10 PM] Starting SSH, verbose level: 2 [7/17/2025 7:53:10 PM] Setting up connection [7/17/2025 7:53:10 PM] Connecting to: 172.16.144.2:22 (IPV_ANY) [7/17/2025 7:53:10 PM] SSH version banner: SSH-2.0-OpenSSH_for_Windows_9.5 [7/17/2025 7:53:10 PM] Sending kex init [7/17/2025 7:53:10 PM] Received kex init [7/17/2025 7:53:10 PM] Selected algorithms: curve25519-sha256(strict), ssh-ed25519, chacha20-poly1305@openssh.com, chacha20-poly1305@openssh.com, implicit by cipher, implicit by cipher, none, none [7/17/2025 7:53:10 PM] Sending Ed25519 kex init [7/17/2025 7:53:10 PM] Received Ed25519 kex reply [7/17/2025 7:53:10 PM] Successfully authentified server [7/17/2025 7:53:10 PM] Sending new keys message [7/17/2025 7:53:10 PM] Received new keys message [7/17/2025 7:53:10 PM] Sending userauth service request [7/17/2025 7:53:10 PM] Received extension info message [7/17/2025 7:53:10 PM] Server accepts public key types: ssh-ed25519,sk-ssh-ed25519@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com,ssh-dss,ssh-rsa,rsa-sha2-256,rsa-sha2-512 [7/17/2025 7:53:10 PM] Received service accepted message [7/17/2025 7:53:10 PM] Sending userauth init request [7/17/2025 7:53:10 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:53:10 PM] Starting interactive authentication [7/17/2025 7:53:10 PM] Sending userauth interactive request [7/17/2025 7:53:11 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:53:11 PM] Starting password authentication [7/17/2025 7:53:17 PM] Sending userauth password request [7/17/2025 7:53:17 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:53:17 PM] Starting password authentication [7/17/2025 7:53:22 PM] Bytes sent: 1496, Bytes received: 1820 [7/17/2025 7:53:22 PM] Packets sent: 7, Packets received: 8 [7/17/2025 7:53:22 PM] Kex completed: 1 [7/17/2025 7:53:41 PM] Devolutions.ProtocolsSharp: 2025.7.1.1 OS: Windows [7/17/2025 7:53:41 PM] Terminal font: Consolas [Consolas, fixed=True] [7/17/2025 7:53:41 PM] Starting SSH, verbose level: 2 [7/17/2025 7:53:41 PM] Setting up connection [7/17/2025 7:53:41 PM] Connecting to: 172.16.144.2:22 (IPV_ANY) [7/17/2025 7:53:41 PM] SSH version banner: SSH-2.0-OpenSSH_for_Windows_9.5 [7/17/2025 7:53:41 PM] Sending kex init [7/17/2025 7:53:41 PM] Received kex init [7/17/2025 7:53:41 PM] Selected algorithms: curve25519-sha256(strict), ssh-ed25519, chacha20-poly1305@openssh.com, chacha20-poly1305@openssh.com, implicit by cipher, implicit by cipher, none, none [7/17/2025 7:53:41 PM] Sending Ed25519 kex init [7/17/2025 7:53:41 PM] Received Ed25519 kex reply [7/17/2025 7:53:41 PM] Successfully authentified server [7/17/2025 7:53:41 PM] Sending new keys message [7/17/2025 7:53:41 PM] Received new keys message [7/17/2025 7:53:41 PM] Sending userauth service request [7/17/2025 7:53:41 PM] Received extension info message [7/17/2025 7:53:41 PM] Server accepts public key types: ssh-ed25519,sk-ssh-ed25519@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com,ssh-dss,ssh-rsa,rsa-sha2-256,rsa-sha2-512 [7/17/2025 7:53:42 PM] Received service accepted message [7/17/2025 7:53:42 PM] Sending userauth init request [7/17/2025 7:53:42 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:53:42 PM] Starting interactive authentication [7/17/2025 7:53:42 PM] Sending userauth interactive request [7/17/2025 7:53:42 PM] Received userauth failure: publickey,password,keyboard-interactive [7/17/2025 7:53:42 PM] Starting password authentication [7/17/2025 7:53:42 PM] Sending userauth password request [7/17/2025 7:53:42 PM] Received userauth success [7/17/2025 7:53:42 PM] User authenticated successfuly by password [7/17/2025 7:53:42 PM] Sending session channel open request: 0|- [7/17/2025 7:53:42 PM] Received global request: hostkeys-00@openssh.com, no need to reply [7/17/2025 7:53:42 PM] Received channel open confirmation: 0|0 WS 200000|0 MPS 32000|32768 [7/17/2025 7:53:42 PM] Sending pty request: 0|0 xterm-256color, 198x42 [7/17/2025 7:53:42 PM] Received channel success: 0|0 [7/17/2025 7:53:42 PM] Sending environment variable request: LANG=en_US.UTF-8 0|0 [7/17/2025 7:53:42 PM] Received channel failure: 0|0 [7/17/2025 7:53:42 PM] The server did not accept the environment variable [7/17/2025 7:53:42 PM] Sending shell request: 0|0 [7/17/2025 7:53:43 PM] Received channel success: 0|0
Hello,
We cannot reproduce this issue as of now. One thing we would like to know is if you are using either the "Automatically open the file transfer tab" option in your SSH entry's properties or the SFTP toggle button in the opened entry?
If you are, could you try without that option and see if the error still happens?
Another thing we would like to know is if you have any syntax highlighting configured on your entry.
Best Regards,
@Michael Beaudin
Hello @Michael Beaudin
unfortunately i couldn't find SFTP blade 
a4087cca-7f41-4d8e-920e-90e756189397.png
Hello Soheil,
That was a mistake on my end. The screenshot I have shown you is only what it will look like in the next major version of RDM (2025.3.x.x). The version you have access to will instead be in Terminal -> Advanced.
Also we would like to know if you use any syntax highlighting in your SSH entries. 
Once we have this information as well as the information you have provided us earlier, it should be easier for our terminal expert to fix this issue once he is back from vacation next week.
Best Regards,
Michaël Beaudin
bbe2ee6b-1316-4f6c-8274-f23b3d9bfac6.png
0e532a9c-9d31-4f4e-910b-49dba8f9a2dc.png
Hello Soheil,
That was a mistake on my end. The screenshot I have shown you is only what it will look like in the next major version of RDM (2025.3.x.x). The version you have access to will instead be in Terminal -> Advanced.
Also we would like to know if you use any syntax highlighting in your SSH entries.
Once we have this information as well as the information you have provided us earlier, it should be easier for our terminal expert to fix this issue once he is back from vacation next week.
Best Regards,
@Michael Beaudin
hello
thanks for you help. here is SFTP information
and this is display blade information 
if you are looking for syntaxes highlights configuration, YES i change default profile configuration and it apply to all of my sessions.
d94968f2-bf44-4018-ae61-63fed0818c8c.png
c278d352-393c-4d5c-aabf-0bfa003848e3.png
f41aec5b-32a4-4b35-9ef0-7cc11a1c4ac3.png
Hello,
Thank you for the information. We have created a ticket on our end and will let you know of any progress or further questions we have.
Best Regards,
Michaël Beaudin
Hello,
This issue should be fixed starting with our next minor version, 2025.2.23.0. If you still encounter the issue after this version is released, please let us know.
Regards,
Hubert Mireault
hello
i want to inform you that issue has been resolved. thanks for your assistance
20a7d028-47c6-4ec5-919c-58c595031ef0.png
I'm glad to hear it! Let us know if there's anything we can help you with.
Regards,
Hubert Mireault