Error: An error occurred while switching to Coherence

Symptoms

When trying to switch to Coherence view mode I get the following error message:

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

Cause

This may happen due to the following reasons:

• Antiviral software or Firewall inside your virtual machine are blocking access to Coherence tool for Parallels Desktop processes.
• Virus or malware inside your virtual machine are blocking access to Coherence tool for Parallels Desktop processes.
• Internal error in Coherence tool service.

Resolution

Do the following inside your virtual machine:

Antiviral software or Firewall:

1.  Disable antivirus protection and Firewall.

• If the problem disappeared, try to add the following processes to the list of exceptions in your antivirus program:

coherence.exe    (full path: C:\Program Files (x86)\Parallels\Parallels Tools\Services\coherence.exe)

prl_hook.dll         (full path: C:\Program Files (x86)\Parallels\Parallels Tools\Services\prl_hook.dll )

• If you managed to do it, you may enable the protection back.
• If the problem is still there, check if you have ViPNet Client program installed in your virtual machine. Uninstall that program if you found it. ViPNet Client is a protective software which blocks Parallels Desktop services and provides no options to add certain services to exceptions.

Virus or malware:

1. Make sure you have no viruses. If you are not sure, check Windows using this utility by Dr.Web: Dr.Web CureIt!

   • In case a virus has been found, remove Parallels Tools from Control Panel > Add and remove Programs, remove virus and install Parallels Tools back.

Internal error in Coherence tool service:

1. If the issue is still present, make sure that Parallels Coherence Service is running inside your virtual machine:

   • Press CMD + R > type services.msc > Hit Return/Enter.
   • Find Parallels Coherence Service in the Services tab and make sure it is in running state.
   • If it is already running, try restarting it.
   • If it does not help, Shut down you virtual machine from Actions > Shut Down. Leave it in stopped state for a while and Start.

Related articles:

Cannot enter Coherence mode after upgrading to Windows 8.1

Cannot enter Coherence, it hangs with "Starting Coherence" spinning wheel

Unable to switch to Coherence mode

#- INTERNAL -#

WARNING: this article is linked with PD Error Reporting. Do not modify this article without consulting with CPA Trainers.