Error message: A copy of Postbox is already open

When starting up Postbox if you receive the following error message:

"A copy of Postbox is already open.  Only one copy of Postbox can be open at a time."

The cause may be that Postbox is still running, or a lock on your profile may still be in place.

Kill the Process

macOS

1. Open the Activity Monitor application.
2. Quit the Postbox process.

Windows

1. Right-click on the taskbar, and select Task Manager.
2. Select the Postbox process.
3. Click End Task.

Remove the Profile Lock

A lock file is created in your Postbox profile to prevent other instances from writing data to it while Postbox is running. Postbox may have previously exited without deleting the lock file.

1. Restart your computer.
2. Go to your Postbox profile folder - see Postbox Profile Data.
3. Delete the following file:
   • (macOS) .parentlock
   • (Windows) parent.lock

Make sure you have the correct profile set within the "profiles" configuration file

If you copied a profile folder over, you may need to change your profiles file. Within your Postbox directory will be a file called "profiles.ini" which will contain the following lines:

[General]
StartWithLastProfile=1

[Profile0]
Name=default
IsRelative=1
Path=Profiles/46crnd2o.Default

Make sure that the Path=Profiles/xxxxx.xxxx is set to the same name as your default profiles folder.

Reset your Profile

The issue may still be specific to your Postbox profile. To find out, open the Postbox Profile Manager, and create a new profile.

macOS

1. Open the Terminal application.
2. Enter the following command:
   /Applications/Postbox.app/Contents/MacOS/postbox-bin -profilemanager
3. Press Return.
4. If the profile manager opens, click Create Profile, and follow the prompts to create a new profile.
5. Use the instructions in the following article to migrate your essential data to the new profile: How to Migrate Essential Data to a New Profile

Windows

1. Press the Windows logo key  + R on the keyboard, then type in the following:
   postbox.exe -ProfileManager
2. Press Enter.
3. If the profile manager opens, click Create Profile, and follow the prompts to create a new profile.
4. Use the instructions in the following article to migrate your essential data to the new profile: How to Migrate Essential Data to a New Profile