Bitwarden sync on macOS – “Base URL must not be null or empty” with custom host

Hi Devolutions Support,

I’m having trouble using the Bitwarden synchronization in Remote Desktop Manager for macOS with a self-hosted Bitwarden server.

Environment

• Remote Desktop Manager for macOS: 2025.3.7.3 (64-bit)
• macOS (Apple Silicon)
• Bitwarden: self-hosted (Vaultwarden), HTTPS with a valid certificate
• Access to the web vault via browser works fine from the same machine
• TLS Diagnostics in RDM against the server URL are all green (handshake and certificate chain OK)

Bitwarden sync configuration in RDM

• Host: Custom
• URL: custom self-hosted Bitwarden base URL (HTTPS, no path suffix)
• Client ID / Client Secret: personal Bitwarden API key (user API key)
• Master password: same password I use for the Bitwarden vault

When I run the synchronization, I get a popup:

Unable to retrieve Bitwarden credentials

In the application log I see the following error (repeating for each attempt):
Error: System.ArgumentException: Base URL must not be null or empty Arg_ParamName_Name, baseUrl
at PasswordManagerAccess.Bitwarden.Client.MakeRestClient(String baseUrl, IRestTransport transport)
at PasswordManagerAccess.Bitwarden.Client.LogInCliApi(ClientInfoCliApi clientInfo, String baseUrl, IRestTransport transport)
at PasswordManagerAccess.Bitwarden.Client.LogIn(ClientInfoCliApi clientInfo, String baseUrl)
at PasswordManagerAccess.Bitwarden.Client.Open(ClientInfoCliApi clientInfo, String baseUrl)
at Devolutions.RemoteDesktopManager.Managers.BitwardenManager.InitializeAPIKey(String clientId, String clientSecret, String password, BitwardenHostMode hostMode, String customUrl, Boolean isSilent)

This suggests that the Bitwarden library receives a null or empty base URL, even though a custom URL is configured in the sync entry and passes TLS Diagnostics.

It looks like the custom URL might not be passed correctly from the macOS UI to the Bitwarden client when using Host = Custom with API key authentication.

Could you please check if this is a known issue on macOS or advise on a workaround?
If helpful, I can provide the full log file and screenshots of the Bitwarden sync configuration.

Best regards,
Michael