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Error: An error occurred while switching to Coherence

APPLIES TO:
  • Parallels Desktop

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:

  • Aniviral 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.
  • We recommend to use Kaspersky Internet Security, for more information please refer to the following KB: #112773
  • 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




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