If Microsoft Excel is coming up with “Microsoft has blocked Macros from running because the source of this file is untrusted” message, it is likely that you are either trying to open a macro-enabled file or trying to execute a macro inside an already-opened file.
The reason for this message is due to a built-in security feature in Microsoft Excel and other Office apps; which requires them to block execution of macros in all files that have the “Mark of the web” (MOTW) tag attached to them.
This results in Macro-enabled files being automatically restricted/blocked by Microsoft Excel; if they were downloaded from the internet, received as Email attachments, downloaded from a cloud storage location or stored at an unsafe location (Network shares, external drives and folders not marked as trusted locations).
Microsoft Has Blocked Macros from Running
While “Mark of the web” security feature in Microsoft Excel, Word and other Office Apps is designed to protect the computer from malware delivered through VBA Macros, it results macros in legitimate files being blocked.
However, this issue can be easily fixed by manually unblocking the macro-enable file and by moving the File to a trusted location.
Method 1: Manually Unblock the Excel File
If Microsoft Excel is preventing you from opening a particular macro-enabled file or running macros on an already-opened file, you should be able to fix the problem by manually unblocking the file.
1. Close the workbook (if it is open) and navigate to the location; where the file is located.
2. Right-click on the File and select Properties in the drop-down menu.
3. On the File Properties screen, switch to General tab and select the Unblock option; located in the “Security” section.
Note: Move to the second method, if the “Unblock” check box is missing
4. Click on Apply and OK to save the changes.
5. After this open the Excel file and click on the View tab > click on Macros tab and select View Macros option.
6. On the next screen, click on the Run button to run macros
2. Move File to Trusted Folder Location
If the “Unblock” checkbox is missing, the problem is due to the macro-enabled file being located at an unsafe location (Network shares, external drives and folders not marked as trusted locations).
The solution in this case is to move the file from its current untrusted location to a Folder on Desktop and designate this as a safe location on your computer.
1. Move the locked Excel file to a Folder on the computer.
2. Open the Excel File and click on the File tab located in top-menu bar.
3. Scroll down the File Menu and click on the Options tab.
4. On “Excel Options” screen, click on Trust Center in the left-pane. In the right-pane, click on the Trust Center Settings button.
5. On “Trust Center” screen, select Trusted Locations in the left-pane and click on Add new location button in the right-pane.
6. On “Microsoft Office Trusted Location” screen, click on the Browse button and select the Folder in which the Excel File is located.
7. After the path to Folder in which the blocked file is located appears, check the little box next to Subfolders of this location are also trusted and click on OK.