IDE fails to start: DirectoryLock CannotActivateException with suppressed BindException

Symptoms

The IDE fails to start, and a "Start Failed - Internal error" dialog appears with the following message:

com.intellij.platform.ide.bootstrap.DirectoryLock$CannotActivateException:
Process "<path to IDE binary>" (<PID>) is still running and does not respond.

Cause

A previous IDE process is still alive (or did not shut down cleanly), and the lock file in the IDE configuration directory is still held by that process (Start Failed (BindException: Address already in use: bind))

Resolution

Step 1: Terminate the stuck IDE process

Windows:

1. Open Task Manager (Ctrl+Shift+Esc).
2. Switch to the Details tab.
3. End every process matching the IDE binary, for example idea64.exe, webstorm64.exe, pycharm64.exe.
4. Start the IDE again.

macOS:

1. Open Activity Monitor.
2. Find the IDE process by name (for example idea, webstorm, pycharm).
3. Select it and click the stop button (×) in the toolbar, then choose Force Quit.
4. Start the IDE again.

Linux:

pkill -f <ide-binary-name>

Step 2: Delete the stale lock file (only if Step 1 does not resolve the error)

The .lock file lives in the IDE configuration directory. Default locations:

Procedure:

1. Close the IDE completely.
2. Open the configuration directory above. <Product><Version> follows the major.minor pattern, for example WebStorm2025.3, IntelliJIdea2025.3.
3. Delete .lock (and the port and token files if present).
4. Start the IDE again.

See Directories used by the IDE for full details on configuration directory locations.