Salesforce for Outlook (SFO) Side Panel Keeps Spinning and Never Connects in Microsoft Outlook

This article provides step-by-step troubleshooting instructions for the Salesforce for Outlook (SFO) Side Panel spinning issue in Microsoft Outlook. Salesforce for Outlook (SFO) is a desktop integration plugin that connects Microsoft Outlook with Salesforce CRM and displays Salesforce record information in a panel within Outlook. Follow the steps below in order, testing after each step before proceeding.

Step 1: Check Internet Explorer Compatibility Mode

Depending on the URL used to connect to Salesforce — whether the default login.salesforce.com, a Single Sign-On URL, or a Custom Domain — you may need to ensure that Internet Explorer 11 (IE11) is not configured to use any of these URLs in Compatibility Mode.
To test whether the Side Panel is using the correct browser emulation:

1. Open IE11 and press F12 to open the F12 Developer Tools.
2. Click on the Emulation tab in the Developer Tools.
3. In the IE11 address bar, enter your Salesforce login URL followed by: clients/sidepanel/sidepanelcontainer.apexp
4. Once the page loads, check the Document Mode value. It must show 11 (Default). Any other value means the browser emulation registry value is not correctly set.

If the Document Mode shows 7, follow these steps:

1. In Internet Explorer, click the Tools button and select Compatibility View Settings.
2. Uncheck both Display Intranet sites in Compatibility View and Use Microsoft Compatibility Lists.
3. Click Close and test again.

Image: Screenshot showing Internet Explorer Compatibility View Settings with both checkboxes unchecked.
Image: Example of SFO Side Panel working correctly when browser emulation is not the cause.
Image: Example of SFO Side Panel in Compatibility Mode — spinning behavior.

Step 2: Verify Browser Emulation Registry Keys

For the SFO Side Panel to connect and display content correctly, the Internet Explorer browser emulation values in the Windows Registry must be set to IE11 — even if the user's default browser is Chrome or Firefox.
First, confirm you have the latest version of Internet Explorer installed. If not, contact your IT Help Desk to upgrade.
Note: The following registry steps require local administrative rights on the computer.

1. Click the Start button, type Regedit, and press Enter to open the Windows Registry Editor.
2. Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\MAIN\FeatureControl\FEATURE_BROWSER_EMULATION
3. Click FEATURE_BROWSER_EMULATION in the left pane.
4. In the right pane, confirm that both OUTLOOK.EXE and SfdcMsOl.exe exist with values set to 11000 or 11001.
5. If either value does not exist, create it by right-clicking in the right pane, selecting New | DWORD (32-bit), naming it OUTLOOK.EXE (or SfdcMsOl.exe), and setting its Decimal value to 11000.

Repeat the same verification for the following additional registry keys:

• HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION
• HKEY_CURRENT_USER\Software\Wow6432Node\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION (if it exists)
• HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\MAIN\FeatureControl\FEATURE_BROWSER_EMULATION

Note: If another application on the computer requires a different value for this key, the value may revert after restarting Outlook or the machine. Check these registry values after each restart to confirm they remain correct.

Step 3: Set the BrowserEmulationModeConfig Registry Key

Microsoft has documented that custom add-ins may not display all fields correctly in Outlook without a specific registry value. To apply the fix:

1. Close all Outlook instances and exit SFO from the System Tray icon.
2. Open the Registry Editor (press Windows + R, type REGEDIT, press Enter).
3. Navigate to: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options
4. In the Options folder, right-click in the right pane and select New | DWORD (32-bit) Value.
5. Name the new value: BrowserEmulationModeConfig
6. Double-click the value, select Decimal, and enter 3.
7. Click OK, close all windows, and test.

If BrowserEmulationModeConfig already exists, confirm its value is set to 3 and not 1 or any other value.

Step 4: Configure Internet Explorer Settings

Ensure all Internet Explorer windows and running programs are closed before starting.

1. Press Windows + R, type Inetcpl.cpl, and click OK to open Internet Explorer Settings.
2. Advanced tab: Click Restore Advanced Settings, then click Reset. Select Delete Personal Settings, then click Reset. Click Close.
3. General tab: Click Delete... under Browsing History. Deselect Preserve Favorites website data; select Temporary Internet files and website files and Cookies and website data. Click Delete.
4. General tab: Click Settings under Temporary Internet Files and History Settings. Select Every time I visit the webpage and enter a value between 50–250 in the Disk space to use field.
5. Security tab: Click Trusted Sites, then Sites. Add the following URLs: <REDACTED> <REDACTED> `<REDACTED> plus any custom domain or Single Sign-On URL you use to log in to Salesforce.
6. Security tab: With Trusted Sites selected, click Custom level.... In the Reset to field, select Low and click Reset. Enable the following settings: Websites in less privileged web content zone can navigate into this zone (under Miscellaneous), Display mixed content (under Miscellaneous), and Initialize and script ActiveX controls not marked as safe for scripting (under ActiveX controls and plug-ins).
7. Privacy tab: Click Advanced, select Accept under First-party cookies, Accept under Third-party cookies, and Always allow session cookies. Click OK.
8. Advanced tab: Ensure Use TLS 1.1 and Use TLS 1.2 are checked. Ensure Check for server certificate revocation, Do not save encrypted pages to disk, and Empty Temporary Internet Files folder when browser is closed are unchecked.
9. Connections tab: Click LAN settings. Ensure no proxy settings are selected unless your network administrator has specified otherwise.
10. Close Internet Explorer Settings, restart the browser, and test.

Step 5: Check for Duplicate Library Registry Keys

Open the Registry Editor and navigate to: HKEY_CLASSES_ROOT\TypeLib\{00062FFF-0000-0000-C000-000000000046}
Under this key, only one subkey should exist, corresponding to the version of Microsoft Outlook currently installed:

• 9.2 — Office 2003
• 9.3 — Office 2007
• 9.4 — Office 2010
• 9.5 — Office 2013
• 9.6 — Office 2016
• 9.7 — Office 2019

If two subkeys are present (for example, 9.3 and 9.4), delete the one that does not match your currently installed version of Outlook. An extra key from a previously installed version can cause the Side Panel to misbehave.

Step 6: SFO Version 3.4.5 Specific Fix

SFO installer version 3.4.5 may automatically add the BrowserEmulationModeConfig registry key and set its value to 2 instead of 3. To fix:

1. Remove the existing BrowserEmulationModeConfig key from HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options.
2. Upgrade SFO to the latest version.
3. Re-add the key with a value of 3 following the steps in Step 3 above.