**⇒ Important Note**: [Back up your Outlook data](https://support.microsoft.com/en-us/office/back-up-your-email-e5845b0b-1aeb-424f-924c-aa1c33b18833) before pursuing the solutions below.
## Launch Outlook in Safe Mode Press the Windows and R keys to launch a new **Run** **window**. Then type **Outlook.exe /safe**, and hit OK. [](https://book.msls.tech/uploads/images/gallery/2023-08/C3Uimage.png)If the issue is gone in Safe Mode, most likely, your add-ins are to blame. Go to the next step and disable your add-ins.
## Disable Your Add-Ins 1. Launch Outlook and go to **File**. 2. Select **Options**, and click on **Add-ins**. 3. Click on **Manage** and hit the **Go** button. [](https://book.msls.tech/uploads/images/gallery/2023-08/aPNimage.png) 1. Select the add-ins you want to disable and save the changes. Don’t forget to update your Outlook version. Click on **File**, select **Office Account**, and go to **Office Update**. Click on **Update Options** and select **Update now** to update your email client. [](https://book.msls.tech/uploads/images/gallery/2023-08/9kVimage.png) ## Recreate Your Email Profile Some users were able to fix this error by recreating their email profiles. 1. Type *regedit* in the Windows Search bar and launch the Registry Editor. 2. Then, navigate to **Computer\\HKEY\_CURRENT\_USER\\SOFTWARE\\Microsoft\\Office\\16.0\\Outlook\\Profiles** 3. Go ahead and delete all the folders listed under **Profiles**. - **Note**: Depending on your Office version, you may need to navigate to Computer\\HKEY\_CURRENT\_USER\\SOFTWARE\\Microsoft\\Office\\15. 4. Relaunch Outlook and recreate your email profile. 5. Go to **File**, select **Account Settings,** and click on **Manage Profiles.**[](https://book.msls.tech/uploads/images/gallery/2023-08/NDnimage.png) 6. Then go to **Show Profiles** and hit the **Add** button. 7. Enter all the necessary details in the Profile Name box and save the changes. [](https://book.msls.tech/uploads/images/gallery/2023-08/opWimage.png)Alternatively, if you’re not comfortable using the Registry Editor, you can only follow the steps from 5 to 8 to create a new profile.
If you can’t create a new profile using Outlook, go to Control Panel → Mail → Show Profiles → Add.
## Repair Office 1. Go to Control Panel and select **Programs**. 2. Click on **Programs and Features** and select your Office package. 3. Hit the **Change** button and launch the **Quick Repair** tool. 4. If the error persists and you still can’t use Outlook properly, run the **Online Repair** tool as well. 1. [](https://book.msls.tech/uploads/images/gallery/2023-08/Qt9image.png) ## Repair Outlook 1. Go to **Settings** and select **Apps**. 2. Then click on **Apps and Features** and select **Outlook** (or Outlook Desktop Integration). 3. Go to **Advanced options** and hit the **Repair** option. 4. [](https://book.msls.tech/uploads/images/gallery/2023-08/jZ1image.png) Alternatively, you can repair the Outlook data file (.pst) file directly. 1. Close Outlook and navigate to **Outlook 2016/2019: C:\\Program Files (x86)\\Microsoft Office\\root\\Office16** or **Outlook 2013: C:\\Program Files (x86)\\Microsoft Office\\Office15** (depending on your Office version). 2. Locate and run **SCANPST.EXE**. 1. [](https://book.msls.tech/uploads/images/gallery/2023-08/ZOwimage.png) 1. Click on **Browse** to select the Outlook Data File (.pst). 2. Hit the **Start** button and then select the **Repair** option. #### Run Microsoft’s Support and Recovery Assistant There’s another handy tool that you can use to repair Outlook. The Microsoft Support and Recovery Assistant can quickly find and repair various Office and Outlook issues. [Download the tool from Microsoft](https://support.microsoft.com/en-us/office/about-the-microsoft-support-and-recovery-assistant-e90bb691-c2a7-4697-a94f-88836856c72f), install it on your computer, and follow the on-screen instructions to repair Outlook. ## Reduce Outlook Data Size Large mailboxes can take an awful lot of time to open. Apart from that, they may also trigger various errors while loading. Reduce the size of your mailbox and Outlook data files and check if the error persists. 1. Launch Outlook, click on **File**, select **Tools**, and click on **Mailbox Cleanup**. [](https://book.msls.tech/uploads/images/gallery/2023-08/f5Nimage.png) 2. Select the items you want to remove and confirm your choice. 3. To reduce the size of the data file, empty the **Deleted Items** folder. 4. Then click on **File**, and select **Account Settings**. 5. Go to the **Data Files** tab, and select the file that you want to compact. 6. Go to **Settings** and hit the **Compact Now** option. [](https://book.msls.tech/uploads/images/gallery/2023-08/fl5image.png) Exchange and Outlook.com users need to click on **Settings** → **Advanced** → **Outlook Data File Settings**. ### Reinstall Outlook If you’re using the standalone desktop app, uninstall it and restart your computer. Then download Outlook again (the 64-bit version). If the error persists, go to **Control Panel** and select **Uninstall a program**. Then uninstall your Office package, restart your machine again and reinstall Office. Check the results. ### Conclusion Microsoft Outlook may sometimes fail to launch with the “*The set of folders cannot be opened*” error. To fix it, launch Outlook in Safe Mode and disable your add-ins. Then repair Office and Outlook, create a new user profile and reinstall the email client. Which of these solutions worked for you?