Overview

If your Outlook profile doesn’t load at all while using the Kerio Outlook Connector (KOFF), this issue is typically caused by corrupted cache files or configuration inconsistencies between the client and server.

Symptoms include:

• Outlook remains stuck on “Loading Profile”

• KOFF icon in the Windows taskbar shows an error status

• Outlook crashes or fails to start when attempting to access the profile

This article walks you through progressive troubleshooting steps — from safe, non-destructive cache clearing to full profile recreation and advanced server-side reset actions.

Solution

Step 1: Manually Clear Outlook KOFF Cache (Least Invasive)

Clearing the KOFF cache only removes local data stored on the client computer. It does not affect actual mailbox data on the server.
Follow one of the 2 resources below:

👉 Rebuilding KOFF Profile on Windows

👉 Manually Clearing Outlook KOFF Cache on Client PC

After clearing the cache, restart Outlook and check if the profile loads successfully.

Step 2: Remove and Recreate the KOFF Profile

If the issue persists after clearing the cache:

1. Delete the existing KOFF profile from Control Panel → Mail → Profiles.

2. Manually create a new profile following this guide:
   👉 Creating Kerio Outlook Connector (KOFF) Profiles in Microsoft Outlook Manually

Step 3: Reset the KOFF Cache (Client + Server Side)

When profile recreation doesn’t help, perform a complete reset from both sides.
Follow the detailed instructions here:
👉 Recreating an Outlook Profile When Using the Kerio Connector

Step 4: Configure Antivirus Exclusions for Kerio Connect

Antivirus software — including Microsoft Defender — can sometimes block Kerio files even when disabled.
Add the following folder exclusions in your antivirus settings (Antivirus Exclusions for Kerio Connect) - especially if you are using Microsoft Defender, even if it is disabled.

C:\Program Files (x86)\Kerio\Outlook Connector (Offline Edition)
C:\Users\<username>\AppData\Local\Kerio\Outlook Connector
C:\Program Files (x86)\Kerio\UpdaterService

After applying exclusions, perform again:

1. Manual KOFF Cache Clear, and

2. Outlook Profile Recreation (if necessary).

Step 5: Collect Diagnostic Data (If Issue Persists)

If Outlook still fails to load:
  Gather the following information for advanced troubleshooting:

1. KOFF Debug Logs from the client PC:

   • Guide: Locating the KOFF Store and the Debug Files

2. Screenshot from Outlook → File → Office Account

3. Screenshot of the KOFF icon status from the Windows taskbar (hover over the icon to capture the status message)

Summary

If Outlook fails to load when using Kerio Outlook Connector (KOFF), start by clearing the local cache and recreating the profile. If that fails, reset the cache both client- and server-side. Finally, ensure antivirus exclusions are in place to prevent file blocking. Collect logs and screenshots for further escalation if the issue persists.

FAQ

Q1: Will clearing the KOFF cache delete my emails or contacts?
A: No. Clearing the KOFF cache only removes local copies. All mailbox data remains safely stored on the Kerio server.

Q2: How can I tell if my KOFF profile is corrupt?
A: If Outlook consistently hangs on “Loading Profile” or shows sync errors even after restarting, the profile is likely corrupted.

Q3: Why do I need antivirus exclusions even if my AV is disabled?
A: Microsoft Defender and other AVs can still apply kernel-level file blocking even when “disabled.” Adding exclusions ensures uninterrupted KOFF operation.