Fix: Extension Won't Load

Extension host crashed

One extension crashing can take down the entire extension host — every extension stops working. This is the most common cause of "extension not loading."

Check: Bottom status bar — does it show "Extension host not responding"?

Find the culprit:

# Open the Extension Logs folder
Command Palette → "Developer: Open Extension Logs Folder"

# Look at the most recent log file
# The last extension mentioned before the crash is your culprit

Fix: Disable the crashing extension via the Extensions panel. Reload window. Re-enable only if you can update it or find an alternative.

Version incompatibility

The extension requires a newer VS Code version than you have, or it's built for older APIs you don't run anymore.

Check:

1. Open the extension's page in the marketplace
2. Look at "Requires VS Code" version
3. Compare with your VS Code version (Command Palette → "About")

Fix: Update VS Code, or downgrade the extension to an older version that supports your VS Code.

// In the Extensions panel:
// 1. Find the extension
// 2. Click the gear icon
// 3. Select "Install Another Version..."
// 4. Choose a version compatible with your VS Code

Corrupted install

The extension files exist but are incomplete or damaged. Happens after interrupted installs or disk issues.

Symptoms: The extension shows in the list but its description is empty, or it lacks an icon, or its features are missing but no error appears in the Running Extensions panel.

Fix — reinstall cleanly:

# 1. Uninstall via Extensions panel
# 2. Restart VS Code completely
# 3. Reinstall from the marketplace

# Or delete the folder directly:
# macOS/Linux:
rm -rf ~/.vscode/extensions/[publisher].[extension-name]-*

# Windows:
# Delete %USERPROFILE%\.vscode\extensions\[publisher].[extension-name]-*

# Then reinstall via Extensions panel

Activation event hasn't fired yet

Extensions only "activate" when a trigger event happens. A Markdown extension won't activate until you open a Markdown file. A Python extension won't activate until you open a Python file.

Check the extension's activation events on its marketplace page or its package.json. Common events:

• onLanguage:python — activates when a Python file opens
• onCommand:ext.someCommand — activates when a specific command is called
• workspaceContains:**/.git — activates only in git repos
• * — activates immediately (rare, discouraged)

Silent crash or error on activate

The extension tries to activate but immediately throws an error. VS Code logs it but doesn't always notify you.

Read the logs:

Command Palette →
  "Developer: Open Extension Logs Folder"

# Look for the newest log file (usually exthost.log)
# Search for your extension's identifier
# Stack traces there tell you exactly what failed

Common activation errors:

• Cannot find module 'X' — extension wasn't installed completely
• ENOENT: no such file or directory — extension expects a file that doesn't exist
• Permission denied — extension can't read/write the file it needs
• Extension host terminated unexpectedly — the process itself died