# How to fix add-in initialization issues

> Learn how to fix SecureMailMerge add-in issues in Outlook, such as being stuck loading, initialization failures, blank panels, or frozen taskpanes.

## Symptoms

- The add-in panel opens but stays blank or shows a loading spinner indefinitely
- You see a "Loading..." or "Initializing..." message that never completes
- The add-in panel is completely white or empty
- The add-in briefly loads then disappears

## Common Causes

- Browser cache or Outlook web cache is corrupted
- Network connectivity issues blocking the add-in from loading
- Browser storage (cookies/IndexedDB) is blocked by privacy settings
- An outdated version of the add-in is cached
- Corporate proxy or firewall blocking add-in resources

## Step-by-Step Fixes

### 1. Hard refresh the add-in

Close and reopen the email compose window. If using Outlook on the Web, try a hard refresh of the browser page (`Ctrl + Shift + R` or `Cmd + Shift + R` on Mac).

### 2. Clear the Outlook add-in cache

**For Outlook Desktop (Windows):**
1. Close Outlook completely
2. Press `Win + R`, type `%LOCALAPPDATA%\Microsoft\Outlook` and press Enter
3. Delete the contents of the `WebExtCache` or `Wef` folder if present
4. Restart Outlook

**For Outlook on the Web:**
1. Clear your browser cache and cookies for `outlook.office.com` and `outlook.office365.com`
2. Alternatively, try opening Outlook in a private/incognito browser window

### 3. Check that browser storage is not blocked

If your browser blocks third-party cookies or storage access, the add-in cannot start. See our dedicated guide: [Access to browser storage is blocked](https://www.securemailmerge.com/help/browser-storage-blocked/).

### 4. Check your network connection

The add-in needs to load resources from the internet. Verify that:
- Your internet connection is working
- No VPN or proxy is blocking `*.securemailmerge.com`
- Your corporate firewall allows connections to our servers (see [IT Security](https://www.securemailmerge.com/help/it-security/) for required domains)

### 5. Remove and reinstall the add-in

1. In Outlook, go to the **Apps** menu (or **Get Add-ins**)
2. Find SecureMailMerge and click **Remove**
3. Close and reopen Outlook
4. Reinstall from the Apps menu or the [Microsoft AppSource listing](https://appsource.microsoft.com/en-us/product/office/WA200001776)

### 6. Try a different browser or Outlook client

If you are using Outlook on the Web, try a different browser (Chrome, Edge, Firefox). If you are on Outlook Desktop, try Outlook on the Web at [outlook.office.com](https://outlook.office.com) to isolate whether the issue is specific to your Outlook installation.

## Related

- [Browser storage blocked](https://www.securemailmerge.com/help/browser-storage-blocked/)
- [App icon not showing](https://www.securemailmerge.com/help/app-icon-not-showing/)
- [Sending a network log to support](https://www.securemailmerge.com/help/sending-a-network-log-to-support/)