The cannot start Microsoft Outlook error usually pops up right when it is least convenient – just before a big meeting or an important email deadline. This error typically means Outlook’s profile, data file, or add-ins are corrupted or conflicting with something on the system. The good news is that most cases get resolved in under fifteen minutes using the steps below.
Key Takeaways
- The cannot start Microsoft Outlook error is most often caused by a damaged profile, a corrupted PST or OST file, or a misbehaving add-in.
- Running Outlook in Safe Mode quickly isolates whether an add-in is the culprit.
- The built-in Inbox Repair Tool (SCANPST.EXE) fixes the majority of data file corruption issues.
- Creating a new Outlook profile solves problems that repairs alone cannot.
- Keeping Office updated prevents many recurring startup failures.
How to Fix the Cannot Start Microsoft Outlook Error
Work through these steps in order. Most people find the issue resolved by step three, but the later steps are there for the tougher cases.
Step-by-Step Guide
- Step 1: Restart the computer first. This sounds almost too simple, but a stuck background process or a pending update can quietly block Outlook from launching, and a fresh restart clears that out.
- Step 2: Open Outlook in Safe Mode. Press the Windows key and R at the same time, type ‘outlook /safe’ into the box, and press Enter. If Outlook opens normally in Safe Mode, an add-in is very likely the cause.
- Step 3: Disable add-ins if Safe Mode worked. Go to File, then Options, then Add-ins. At the bottom, select ‘COM Add-ins’ from the Manage dropdown and click Go. Uncheck each add-in, click OK, then restart Outlook normally to confirm it opens.
- Step 4: Run the Inbox Repair Tool if Safe Mode did not help. Locate SCANPST.EXE (commonly found under a path like C:\Program Files\Microsoft Office\root\Office16), open it, browse to the Outlook data file (.pst or .ost), and click Start to scan and repair.
- Step 5: Create a new Outlook profile. Open Control Panel, select Mail, click Show Profiles, then Add. Name the new profile, follow the prompts to add the email account, and set it as the default profile before opening Outlook again.
- Step 6: Repair the Office installation. Go to Control Panel, then Programs and Features, select Microsoft Office from the list, click Change, and choose Quick Repair. If that does not resolve it, run Online Repair, which takes longer but replaces more files.
- Step 7: Update Windows and Office. Open Outlook, go to File, then Office Account, then Update Options, and select Update Now. Also check Windows Update separately, since an outdated system component can trigger the same error.
Tip: Before repairing or deleting anything, copy the .pst or .ost data file to a backup folder. That way, no email history is lost even if a repair step does not go as planned.
Common Problems and Fixes
Outlook Still Will Not Open After Safe Mode Works
This usually means an add-in was disabled but not fully removed. Reopen the COM Add-ins list and confirm the checkbox next to the problem add-in stays unchecked, then restart the computer once more before testing Outlook.
SCANPST.EXE Cannot Find the Data File
The default file path varies by Office version and installation type. Search the Windows file explorer for ‘.pst’ or ‘.ost’ directly, or check File, then Account Settings, then Data Files inside Outlook (if it can open at all) to locate the exact path.
New Profile Still Shows the Same Error
This points toward a deeper Office installation issue rather than a profile problem. Move on to the Quick Repair or Online Repair step, since profile-level fixes will not resolve corrupted Office program files.
Error Mentions a Specific Add-in by Name
Tip: If the startup error names the add-in directly, that add-in can be uninstalled through Control Panel, then Programs and Features, instead of guessing which one to disable through trial and error.
Frequently Asked Questions
What does the cannot start Microsoft Outlook error usually mean?
It typically signals a problem with the Outlook profile, a corrupted data file, or an add-in conflict that is preventing the program from loading normally.
Is it safe to delete the Outlook profile and start over?
Yes, creating a new profile does not delete emails stored on the mail server or in the data file, as long as the existing .pst or .ost file is reconnected or backed up first.
How long does the Inbox Repair Tool take to run?
It depends on the size of the data file. Small files finish in a few minutes, while data files several gigabytes in size can take thirty minutes or more.
Will disabling add-ins delete them permanently?
No, disabling an add-in through the COM Add-ins menu only turns it off. It can be re-enabled at any time from the same menu.
What is the difference between Quick Repair and Online Repair?
Quick Repair fixes common issues without an internet connection and finishes faster. Online Repair reinstalls Office entirely and requires internet access, but it resolves deeper corruption that Quick Repair sometimes misses.
Can outdated Windows updates cause this error?
Yes, a pending or failed Windows update can interfere with core Office components, so checking Windows Update alongside Office updates is a worthwhile step.
Does this error happen more often after a new Office update?
It can. New updates occasionally conflict with older add-ins or cached profile data, which is why testing Safe Mode right after an update is a good habit.
What if none of these steps fix the error?
At that point, the issue is likely tied to a deeper Windows user profile or system file problem, and creating a new Windows user account to test Outlook can help confirm that.
Is there a risk of losing emails during these fixes?
The risk is low as long as the data file is backed up before running any repair tool, since most of these steps address the program itself rather than the stored mail data.
