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Cannot Start Microsoft Outlook the Set of Folders Cannot be Opened OST

  Mark Regan
Mark Regan
Published: June 21st, 2025 • 5 Min Read
One of most Irritating error cannot start Microsoft Outlook the set of folders cannot be opened. This startup error prevents users from accessing their emails, calendar, contacts, and other Outlook features. It happens due to several reasons such as corrupted navigation pane, damaged Outlook data files, incompatible add-ins or profile errors. In this tutorial, we will explore the most effective ways to fix Outlook errors and run Outlook smoothly.
Table of Content Hide
  1. Causes & Symptoms of the Error
  2. Universal Fixes for Outlook Startup Failures
  3. Reset Navigation Pane Configuration
  4. Repair Data Files (.pst and .ost)
  5. How to Fix Cannot Start Microsoft Outlook The Set of Folders Cannot be Opened?
  6. Common Questions
  7. Summary

Causes & Symptoms of the Error

  • Outlook store profile UI settings in profile.xml. If this file becomes corrupted, Outlook freezes on loading profile.
  • Symptoms: Error appears when opening Outlook, No access to mailbox interface, Outlook stuck on loading profile.
  • Running Outlook in compatibility mode or using an outdated version of Windows can cause software conflicts.
  • Symptoms: Outlook crashes on startup, Compatibility mode is enabled in shortcut properties, Error occurs after system update or Office update.
  • Corrupted data files, especially large or improperly closed ones can prevent Outlook from open OST file.
  • Symptoms: Outlook hangs during startup, Error appears when restart, Messages like Error detected in Outlook data file.

Universal Fixes for Outlook Startup Failures

If you encounter the error “Cannot Start Microsoft Outlook. The set of folders cannot open. Try these quick and universal solutions first. They often resolve the issue without needing advanced troubleshooting.

Solution 1. Restart Outlook and Your Computer

  1. Close Outlook completely via Task Manager(CTRL+SHIFT+ESC).
  2. Restart your computer.
  3. Open Outlook again and check issues are resolved.Open Outlook

Solution 2. Open Outlook in Safe Mode

  1. Press Win+R and type Outlook.exe /safe and press Ok button.Outlook /safe
  2. If Outlook opens then navigate to file.
  3. Click on options and go to COM:Add-ins and click on Go button.Press Go button
  4. Now, select unnecessary add-ins and remove them.Disable add-ins

A corrupted Navigation is one of the most common reasons for Outlook startup error. Resetting it often fixes the issues without affecting your emails and settings.

Method 1. Use Outlook.exe /resetnavpane Command

  1. Press Win+R to open the Run dialog box.
  2. Type Outlook.exe /resetnavpane.
  3. Hit Enter.

Method 2. Delete Corrupted XML Files Manually

  1. Navigate to C:\Users\%username%\AppData\Roaming\Microsoft\Outlook\.
  2. Delete Outlook.xml file and relaunch Outlook.

Repair Data Files (.pst and .ost)

  1. Locate to SCANPST.EXE : C:\Program Files\Microsoft Office\root\Office16\SCANPST.EXE.
  2. Launch SCANPST Tool and select OST file location as you want to repair.Open Microsoft Outlook Inbox Repair Tool
  3. Make backup of scanned file before repairing and Press on the Repair button.Click on Repair button
  4. Disable Compatibility Mode.
  5. Right-click on Outlook shortcut and click on Properties.
  6. Select Compatibility versions and uncheck Run this program in compatibility mode for.
  7. Click on Apply then press Ok.

How to Fix Cannot Start Microsoft Outlook The Set of Folders Cannot be Opened?

If the manual method doesn’t work then we suggest you choose BitRecover OST to PST Converter as this software allows you to repair an OST file and also can convert in a PST file to easily import in Outlook. This software is completely reliable for individual and batch OST file conversion.

Steps to Fix Microsoft Outlook The Set of Folders Cannot be Opened
  1. Download and launch Automated Software on your pc.
    Microsoft Outlook opened fixer
  2. Click on Configured Outlook mailbox data and press Next button.
    Configured Outlook
  3. Choose OST mailbox folders as you want to recover.
    Select OST mailbox folders
  4. Browse the PST file in the list of Saving options and select PST filters.Choose PST File
  5. Select Advanced filter and destination path as per user comfort.
    Select filter options
  6. Press Next to cannot start Microsoft Outlook the set of folders cannot be opened error solved.
    Microsoft Outlook cannot opened solved
Helpful Features of Recommended Software
  • This software is too beneficial to convert OST to PDF, PST, EML, MBOX, CSV and 39+ export options.
  • It offers a simple to navigate interface to make it a reliable utility for all professional and individual users.
  • You can also import OST to Microsoft 365, Gmail, Thunderbird, Yahoo and all IMAP Supported email platforms.
  • With this wizard, you can also use filter options such as date range, create PST year wise, subject, date range,
Common Questions

What are the Possible Solutions if Outlook is Not Opening?

Restart your PC, run Outlook in safe mode, disable add-ins, reset navigation pane(outlook.exe/resetnavpane), repair data files using ScanPST, or create a new Outlook profile.

How do I Clear the Cache in Outlook?

Close Outlook, then delete cache files from C:\Users\%username%\AppData\Local\Microsoft\Outlook\RoamCache\. You can also clear autocomplete by going to file and clicking on options then hit on Mail and press on Enable AutoComplete List.

How do I force Outlook to Start?

Press Windows+R and type Outlook.exe /safe and then hit Enter. Then start Outlook in safe mode. You can also reset the navigation pane or repair Outlook profile to force it to launch.

Summary

Let sum this article as we have shared all crucial information to fix Cannot Start Microsoft Outlook the set of folders cannot be opened. As we have shared all possible solutions by manually and using Automated software. Both have their own benefits and limitations. Fist try manually if its not done correctly then its happen due to damaged Outlook files repair it and import in Outlook for maintained results.