Unable to enter Coherence mode

Symptoms

• I am not able to enter Coherence view mode.
• Windows explorer.exe app crashes with an error "Windows Explorer has stopped working" after switching to Coherence mode and leads Parallels to switch back to Windows mode.

Cause

The following reasons may cause this:

• anti-Virus program blocking Parallels Coherence Service (e.g. Avira antivirus is known to block Parallels services);
• Parallels Tools corruption;
• an outdated Parallels Desktop build;
• etc.

Resolution

Before proceeding we kindly ask you to send a problem report, that will help our development team to investigate the issue. Thank you in advance.

NOTE: We strongly recommend that you make a backup of the virtual machine before following the below troubleshooting steps.

Now try the below steps. Each of the steps may fix the issue, but if it does not, proceed to the next one.

Step 1 - Update Parallels Desktop if you have multiple displays

If you are using Parallels Desktop 7 for Mac and have multiple displays, please try updating as this article suggests:

112373 - Unable to switch to Coherence with multiple monitors.

Step 2 - An error occurred while switching to Coherence

If you are getting the below error message (exactly the same error message), when trying to switch to coherence view mode:

An error occurred while switching to Coherence. Please try again.
If the problem persists, please contact the Parallels support team for assistance.

Follow this article:

112647 - Error: An error occurred while switching to Coherence

Step 3 - Uninstall all antiviruses

Uninstall anti-virus software from the virtual machine. Or you can add “coherence.exe” and “prl_hook.dll” in antivirus exclusions. Do not forget to install the anti-virus software back, once the problem is resolved.

Step 4 - Reinstall Parallels Tools

As already mentioned above, the issue may be caused by corrupted video drivers inside the virtual machine. Drivers for virtual devices are supplied by Parallels Tools package. Please (re)install Parallels Tools in your virtual machine using these instructions:

8969 - Cannot install Parallels Tools. 4841 - How to reinstall Parallels Tools in Windows Guest OS?

Step 5 - Shut down the VM and then start it again

1. Shut down your Windows virtual machine using the Start menu.
2. Start the virtual machine again.