Outlook Error: "Cannot start Microsoft Outlook. The set of folders cannot be opened."

This error typically occurs when Outlook cannot access your mail profile or its associated data files. This article will help guide you through steps to identify the issue and correct it.

Step 1: Confirm If the Issue Affects Outlook Web Access

Before proceeding with troubleshooting:

✅ Check if you're able to log in through Outlook Web or your mail provider's webmail interface.

If web access works fine, the issue is limited to your Outlook desktop application, and you can proceed with the next steps.

📌 Step 2: Identify Your Email Account Type

Find out what kind of email account you're using:

Exchange / Microsoft 365 — Server-stored data, syncs with the cloud.
IMAP — Server-stored emails, but some calendar/contacts may be local.
POP — All emails are stored locally on your PC unless explicitly configured otherwise.

⚠️ If you are using a POP account, take extra precautions before deleting the profile. POP stores emails locally, and deleting a profile without backing up your .pst file may result in permanent data loss.

Step 3: Delete Corrupted Outlook Profile from Windows Registry

If you're using Outlook 2016 or 2019, follow these steps:

Press Windows + R, type regedit, and press Enter.
Navigate to:

Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Profiles

3. Delete all folders listed under Profiles.

📌 Note for Older Versions:

For Outlook 2013, use:
Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\15.0\Outlook\Profiles
Adjust 15.0, 14.0, etc., depending on your Outlook version.

🔁 Step 4: Recreate the Email Profile

Once the profile is deleted from the registry:

Restart your computer (recommended).
Open Outlook.
Follow the prompts to recreate your profile and re-add your email account.

⚠️ Important: What Happens When You Delete an Outlook Profile?

Exchange/IMAP Accounts: Your emails, contacts, and calendar are synced from the server and will be automatically restored when you sign in again.
POP Accounts: Emails are stored locally on your device in a .pst file.
🔴 If you delete your profile without backing up the .pst file, you risk losing all your email data.
📁 You can back up your POP data by locating the .pst file typically found in:

C:\Users\<YourUsername>\AppData\Local\Microsoft\Outlook

💬 Still Stuck?

Please contact support with the following:

A screenshot of the full error message
Clarify if the issue happens on Outlook Web, Desktop, or both
Mention what kind of email account you're using (POP, IMAP, or Exchange)

We’ll be happy to assist you further.

Tags: Microsoft, Outlook