Cannot start Microsoft Outlook means classic Outlook fails to open the window or the set of folders. Start in safe mode first. Reset the navigation pane and add a new profile next. Repair the data file after that. EmailDoctor Outlook PST Repair Tool saves the mail when Outlook will not open.
Users who cannot start Microsoft Outlook see the message "Cannot open the Outlook window" or "The set of folders cannot be opened". Microsoft lists the error in its article on Outlook that will not start and gives five steps in order.
This guide explains five ways to open Outlook again and keep the mail.
Why You Cannot Start Microsoft Outlook
Four reasons come from Microsoft and community replies:
- Extension conflict. Microsoft says a faulty COM extension can stop Outlook from opening and names an outdated ABBYY FineReader extension as one case.
- Damaged profile. Microsoft says the original profile is corrupt when a new profile starts normally.
- Broken navigation pane settings. Microsoft gives a reset switch for the local navigation pane file.
- Copied profile. Reply in a January 2020 thread on a copied profile says a Laplink copy to a new PC corrupted the profile.
Navigation pane settings belong to one PC. Microsoft says to repeat the reset on every computer where you use Outlook.
Which Method Matches Your Message?
Find the closest message in the first column:
| Message on Screen | Points To | Begin With |
|---|---|---|
| Cannot open the Outlook window | Extension conflict | Method #1 |
| Set of folders cannot be opened | Navigation pane settings | Method #2 |
| Error appears after a PC move or update | Damaged profile | Method #3 |
| Outlook asks for a repair of the data file | Damaged data file | Method #4 |
| Every fix fails and mail is out of reach | Data file needs export | Method #5 |
5 Ways to Fix Cannot Start Microsoft Outlook
Microsoft documents methods 1 to 4. Method 5 needs repair software:
| Action | Source | Watch For |
|---|---|---|
| Safe mode and COM extensions | Microsoft article | Disable and never remove |
| Navigation pane reset | Microsoft article | Local to one PC |
| New profile | Microsoft article and reply | Keep the old profile |
| Inbox Repair Tool | Microsoft article | Needs a backup |
| Scan and export | Product page | Trial item cap |
Method #1: Cannot Start Microsoft Outlook? Open Safe Mode and Check Extensions (Free)
Microsoft says Outlook in safe mode starts without extensions. Follow seven steps:
- Press the Windows key and R together.
- Type
Outlook /safein the Run box and click OK. - Accept the default entry in Choose Profile and click OK.
- Open File, Options and Add-ins when Outlook starts.
- Set Manage to COM Add-ins and click Go.
- Note the names then clear the check boxes without using Remove.
- Close Outlook and open it normally.
Note: Microsoft says to enable the extensions one at a time to find the faulty one. Go to Method #2 when safe mode fails.
Method #2: Reset the Navigation Pane (Free)
Microsoft lists this switch for Outlook that will not open. Use five steps:
- Close Outlook.
- Press the Windows key and R together.
- Type
Outlook.exe /resetnavpanein the Run box. - Click OK.
- Wait for Outlook to open.
Note: Microsoft says the reset applies to one computer only. Repeat the steps on other PCs.
Method #3: Add a New Outlook Profile (Free)
Microsoft says Outlook with a working new profile proves that the old profile is corrupt. Anonymous reply in an April 2020 thread gives these steps and the asker confirmed that they worked. Six steps add the profile:
- Open Control Panel and select Mail.
- Click Show Profiles then Add.
- Create the profile and add your mail account.
- Choose the Prompt for a profile startup option.
- Start Outlook and choose the new profile.
- Keep the old profile until every folder opens.
Note: Microsoft says to backup your data first since removing a profile deletes the offline cache. One later reply in the April 2020 thread succeeded only after deleting every old profile.
Method #4: Repair the Data File With the Inbox Repair Tool (Free)
Microsoft lists the Inbox Repair Tool after the profile step. Reply in a September 2023 thread suggests repairing the data files as well. Six steps repair the file:
- Close Outlook and copy the PST or OST file as a backup.
- Open File Explorer and find SCANPST.EXE in the Office program folder.
- Double click SCANPST.EXE.
- Click Browse and select the data file.
- Click Start and wait for the scan.
- Click Repair when the tool reports errors.
Note: Asker in the September 2023 thread saw that SCANPST.EXE was not recognized. Thread has no confirmed fix.
Method #5: Save the Mail With EmailDoctor Outlook PST Repair Tool (Trial Limit Applies)
EmailDoctor Outlook PST Repair Tool scans damaged PST files and works without Outlook during the scan. EML, PDF, HTML and MSG exports also work without Outlook.
PST export is the exception since it needs Outlook with the Use Outlook option. Copy the PST file and scan the copy.
Scan the PST Copy
Three actions scan the copy:
- Install the repair software and start it on Windows.
- Click Add File and locate the PST copy.
- Choose how to scan and start.
Preview the Mail and Export
Three more actions save the mail:
- Browse the folder tree and check a few messages.
- Click Export and select EML or MSG while Outlook is closed.
- Name a destination folder and begin the export.
Note: EmailDoctor software exports 25 items per folder in the trial version. Buying a license removes the limitation.
What Did You See After the Fix?
Compare your result with these rows:
| Outcome | Verdict | Method |
|---|---|---|
| Safe mode opens and normal mode works after disabling | One extension failed | Method #1 |
| Outlook opens after the switch | Navigation pane file was damaged | Method #2 |
| New profile opens every folder | Old profile was corrupt | Method #3 |
| Outlook opens after the repair | Data file had errors | Method #4 |
| Outlook will not open | Mail needs a safe copy | Method #5 |
Frequently Asked Questions
What Does Cannot Open the Outlook Window Mean?
Outlook failed to open its main window or its set of folders. Microsoft links the message with extensions, a corrupt profile and navigation pane settings.
Does Resetting the Navigation Pane Delete My Mail?
No. Microsoft names the switch for the navigation pane settings file on that PC and does not describe any mail loss. Your mail sits in the data file or on the server.
Does the Trial Version of EmailDoctor Software Export Every Folder?
No. EmailDoctor software exports 25 items per folder in the trial version. Buying a license removes the limitation.
Should I Delete the Old Outlook Profile?
No. Keep it until the new profile shows every folder. Reply in the April 2020 thread says to keep older profiles until everything works.
Can Outlook on the Web Open My Mail Meanwhile?
Yes for mailbox accounts. Anonymous reply in the April 2020 thread suggests Outlook on the web as a stopgap while you fix the desktop app.
Does a Copied Profile Cause This Error?
Yes in one case. Reply in the January 2020 thread says that a Laplink copy corrupted the profile and the fix was a new profile with the accounts added again.
Author’s Verdict
Cannot start Microsoft Outlook points to a damaged profile or a faulty extension most of the time. Start with safe mode because it alters nothing in your data.
Add a new profile when safe mode fails and keep the old one until every folder opens. Backup the data file before any repair.
Choose repair software when the profile and the Inbox Repair Tool both fail. Export the mail to EML or MSG first and settle the cause afterward.
- Microsoft lists safe mode and the navigation pane reset for cannot start Microsoft Outlook.
- Profile and Inbox Repair Tool steps follow.
- Keep the old profile and backup your data first.
- Repair software saves the mail in EML or MSG while Outlook is closed.
Next Read: Compact PST File Without Opening Outlook
Also Read: Outlook MAPI32.DLL Error | Recreate MS Outlook Profile
