Splashtop Remote Control Fails to Launch from the Automox Console (Black Screen, Blank Tab, or st-rmm:// Link)

Issue

When starting a Splashtop remote control session from the Automox console, the session fails to launch. This can appear as any of the following on the workstation launching the session:

• The connection opens but only displays a black screen.
• A blank browser tab opens with an address beginning with st-rmm://com.splashtop.remote.
• A "Splashtop RMM App Required" popup appears, and clicking Yes does nothing.

The issue follows specific operator workstations: other users may be able to connect to the same target devices without any problem, and reinstalling the Splashtop RMM App may not resolve it.

Cause

When you click Remote Control, the console creates the session and hands it to the Splashtop RMM App (Viewer) on the workstation launching the session through an st-rmm:// link. The target device is not involved in this failure; it uses the Splashtop Streamer, which the Automox agent deploys automatically.

The hand-off fails for one of two reasons on the launching workstation:

• Cause 1: The Splashtop RMM App is not installed on the workstation.
• Cause 2: The RMM App is installed, but the st-rmm:// URL protocol handler registration that maps the link to the app is missing from the Windows registry. In some environments the installer completes successfully without creating this registration.

Identify the Cause

1. On the workstation launching the session, confirm whether the Splashtop RMM App is installed. If it is not installed, follow Cause 1 below.
2. If the app is installed (Windows), press Windows key + R, type st-rmm:// and press Enter.
   • If Windows reports it cannot find an app for the link, the protocol handler registration is missing. Follow Cause 2 below.
   • If Windows offers to open Splashtop for RMM, the registration is healthy. Check that your browser is not blocking the site permission to open Splashtop for RMM for console.automox.com, or contact Automox Support.

Cause 1: Splashtop RMM App Is Not Installed

Step 1: Install the Splashtop RMM App

Install the Splashtop RMM App on the workstation you launch sessions from, using the appropriate installer:

• Windows: https://my.splashtop.com/rmm/win
• macOS: https://my.splashtop.com/rmm/mac

Step 2: Retry the Remote Session

After installation completes, return to the Automox console and start a new Splashtop remote control session.

Cause 2: The st-rmm:// Protocol Handler Registration Is Missing (Windows)

First confirm the app's launcher exists at C:\Program Files (x86)\Splashtop\Splashtop Remote\Client for RMM\clientoobe.exe. If your installation uses a different path, substitute it in the steps below.

Warning: These steps edit the Windows registry. Incorrect registry changes can cause system problems. Follow the steps exactly, and back up the registry before making changes.

1. Open Registry Editor (press Windows key + R, type regedit, press Enter, and accept the elevation prompt).
2. Right-click HKEY_CLASSES_ROOT and create a new key named st-rmm.
3. In the st-rmm key, set the (Default) value to URL:ST-RMM Protocol, and add a new String Value named URL Protocol with empty data.
4. Inside st-rmm, create a subkey named shell, inside that a subkey named open, and inside that a subkey named command.
5. Set the (Default) value of the command key to the following, including the quotation marks:
   "C:\Program Files (x86)\Splashtop\Splashtop Remote\Client for RMM\clientoobe.exe" -a "%1"
6. Close and reopen your browser.

Alternatively, save the following as a .reg file and merge it on the affected workstation:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\st-rmm]
@="URL:ST-RMM Protocol"
"URL Protocol"=""

[HKEY_CLASSES_ROOT\st-rmm\DefaultIcon]
@="\"C:\\Program Files (x86)\\Splashtop\\Splashtop Remote\\Client for RMM\\clientoobe.exe\",0"

[HKEY_CLASSES_ROOT\st-rmm\shell]

[HKEY_CLASSES_ROOT\st-rmm\shell\open]

[HKEY_CLASSES_ROOT\st-rmm\shell\open\command]
@="\"C:\\Program Files (x86)\\Splashtop\\Splashtop Remote\\Client for RMM\\clientoobe.exe\" -a \"%1\""

To verify, rerun the Windows key + R test with st-rmm://. Windows should now offer to open Splashtop for RMM. Then start a Remote Control session from the Automox console.

Notes

• Both causes are per-workstation and only apply to the machines admins and helpdesk users launch sessions from. Target devices only require the Splashtop Streamer.
• After installing the Splashtop RMM App on a new workstation, the Windows key + R test above is a quick way to confirm the protocol registration was created before the first session is attempted.