Why does Windows display a “Bad Image” error when using RealVNC applications?

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Issues with Remote Printing

If you are experiencing issues with Remote Printing after updating, please follow the below steps on each remote device running RealVNC Connect or RealVNC Server

What causes the error message to appear?

When using RealVNC applications you may see an error message referring to a "Bad Image", as shown in the screenshot below:

This is caused by RealVNC's new RestrictedMode blocking the action.

RestrictedMode is a security feature that helps protect RealVNC applications on Windows systems.

When enabled, it ensures that only properly signed Microsoft DLLs can be loaded by the RealVNC application, significantly enhancing security.

RestrictedMode is enabled by default in RealVNC Connect 8.4.0, RealVNC Connect Viewer 8.4.0 and RealVNC Server 7.17.0 onwards. 

Disabling RestrictedMode

If you need to RestrictedMode for any reason, for example for compatibility reasons with a separate application you have installed on your device, you can do so by either downloading and applying the Registry patch files below, or manually using Windows' Registry Editor.

Registry Patch Files

All RealVNC Applications

Download

RealVNC Connect All-in-one app

Download

RealVNC Connect Viewer

Download

RealVNC Server

Download

RealVNC Classic Viewer

Download

Using Registry Editor

Manual Steps

To manually create the relevant Registry keys, please follow the steps below:

  1. Open Registry Editor (regedit.exe) with administrator privileges
  2. Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\RealVNC\<appName>
  3. Create a new String value called RestrictedMode, by right clicking in the empty space on the right side of the Registry Editor window and choosing New > String value
  4. Double click the RestrictedMode value and set the value data to 0
  5. Restart the RealVNC application

You will need to manually create Registry Keys for Policies, RealVNC and <appName> if they do not exist.

To create the keys, right click the Software key/folder on the left menu and choose New Key, then enter the key name.

Repeat this for each key of Policies, RealVNC and <appName>.

The list of valid appName values is below:

  • vncviewer
  • vncserver
  • rvncconnect
  • rvncserver

Recommendations

RealVNC recommend that you:

  • keep RestrictedMode enabled unless you have a specific compatibility requirement
  • only disable this feature if absolutely necessary and you understand the security implications
  • ensure any decision to disable RestrictedMode is approved by your IT security team
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