Parallels Toolbox error: Invalid Key

Symptoms

My Parallels Toolbox for Mac installation had suddenly reported that my license key is invalid:

Your license key is invalid for this version of Parallels Toolbox. Please downgrade or buy a new license.

Cause

• Network connection issues;
• A technical issue with Parallels Toolbox.

Before proceeding with troubleshooting, please send a technical report via Help menu > Send Technical Data... > once the report is generated, fill in your contact information and click 'Send Report' button.

Resolution

To resolve this issue, you need to connect to Internet and enter the license key in Parallels Toolbox manually:

1. Visit My Account to find your license key(s).

2. In Parallels Toolbox click at 'I have another key' link:

   

3. Enter and confirm the license key.

Advanced troubleshooting

If the steps above didn't help, please do the following:

1. Make sure your Mac is connected to Internet.

2. Open Terminal.app and execute:

   defaults remove ~/Library/Preferences/com.parallels.toolbox.plist SavedProductVersion
   

3. Restart Parallels Toolbox.app