Unable to start Microsoft 365 and Office: Microsoft Office application is now an important element of our day-to-day life as it deals with our studies, work, business, etc. And as it is a development era Microsoft has launched well-developed and secured products such as Office 365, Office 2019, and also Office 2021 which was precede of Office 365 and Office 2021. You could buy the Office product from the Microsoft product list or store. And in some cases, the installation or update of Office may end up with Unable to start Microsoft 365 and Office
Simple steps to fix Microsoft Unable to start Microsoft 365 and Office
Step 1. Temporarily disable Firewall and Antivirus
Unable to start Microsoft 365 and Office while installing or updating Microsoft Office may occur in case of Network or firewall restrictions. The network rules or firewall rules in the network/computer may block the installation of the Office program or its updating as a part of their security measurements. These firewall rules and Antivirus are implemented on the computer by the network provider or the computer user on its core system or registry.
You could fix the Unable to start Microsoft 365 by disabling the firewall or antivirus temporarily or you could fix the Unable to start Microsoft Office by making creating an exceptional rule for Microsoft Office installation or update.
Follow the steps to disable Firewall to fix Office Unable to start Microsoft 365 and Office:
Step 1. Open the “control panel”
Step 2. Navigate to “System and security” and then to “Windows Firewall”
Step 3. Click on “turn windows firewall On or Off”
Step 4. Select Turn Off Firewall for both private and public networks.
Step 5. Try installing or updating Microsoft Office and check whether the Unable to start Microsoft 365 is fixed.
For more information: click here to view the Microsoft Reference article to disable windows firewall.
Follow the steps to disable Antivirus:
Step 1. Open the Antivirus application installed on the computer.
Step 2. Click on settings and navigate to real-time protection.
Step 3. Turn Off real-time protection.
Step 4. Navigate to the Antivirus firewall.
Step 5. Turn off the Antivirus firewall.
Step 6. Click on YES or OK confirmation prompt if prompted.
Step 7. Try installing or updating Microsoft Office and check whether the Unable to start Microsoft Office is fixed.
Step 2. SFC Scan to fix Office Unable to start Microsoft 365 and Office
Unable to start Microsoft 365 and Office also occurs in case of system file errors or corruption. If Unable to start Microsoft 365 occurred due to the system file corruption, it could be fixed easily by the SFC scan. The SFC scan or system file checking scan is the process of replacing or repairing the corrupted copy of system files using the cached copy of the file from the directory.
Follow the steps to initiate an SFC scan:
Step 1. Open the command prompt in administrative privileges.
Step 2. Type “ sfc /scannow “ and click enter.
Step 3. The scan will begin automatically.
Step 4. Do not close the command prompt until the scan gets completed.
Step 5. Try installing or updating Microsoft Office and check whether the Error is fixed.
For more information: Click here to view Microsoft reference kb article 929833 for sfc scan
Step 3. Registry repair to fix Unable to start Microsoft 365 and Office
Unable to start Microsoft 365 also occurs due to registry corruption or key value errors. A single key value corruption or change may lead to the malfunctioning of the entire Microsoft Office program.
In order to fix the Unable to start Microsoft Office Error it is required to repair the registry keys and rebuilt the string values. And we request you back up the registry before initiating the registry repair as the registry is a highly sensitive element of a computer system and it is recommended to be done in the presence of an Online or offline technician.
For more information on the backup of the registry follow the Microsoft kb article 322756
Follow the steps to repair the registry:
Step 1. Open registry editor
Step 2. Delete the preinstalled or older registry key which blocks the installation of the latest version or update.
Step 3. Navigate the below keys and delete them.
Step 5. Also, change the DWORD values in the below keys from 0 to 1 in Office common registry folder.
Solution 4. Remove and reinstall.
If Unable to start Microsoft 365 is not fixed in registry repair, SFC scan, and firewall/antivirus exception, it is required to remove the Office suite completely from the programs and features, and then reinstall the product for proper use.
Follow the steps given below to fix the Error completely.
Step 1. Open control panel
Step 2. Click on uninstall programs and features
Step 3. Search for Microsoft Office in the list.
Step 4. Select Microsoft Office and click on uninstall.
Step 5. Once uninstall is finished, try running Office setup to install Microsoft Office.
For more information: Click here to view the Microsoft reference kb article to uninstall a program.
How to install Microsoft Office
Step 1. Open Office My Account
Step 2. Log in to your Office account using your registered email ID and password.
Step 3. Click on the install Option under the Office product in your account.
Step 4. Save the installer setup if prompted and run it once the download is completed.
Step 5. Do not go offline or reboot the computer once the installation is initiated.
Step 6. Click on the finish button once the program is installed completely.
Please note: If you are trying to install the School or college or company version of Office suite click here to log in to your office account and then follow step 2.