Background:
When installing the Office 365 connector, the MavimPortalLinkFieldCustomizer (SPFx addon) is set up.
This add-on turns a selected SharePoint term into a hyperlink to the corresponding topic in the Mavim Portal.
However, in some environments, this functionality does not work.
Symptoms:
Users working on unmanaged devices may experience the following:
- The SharePoint column no longer displays the selected term after the script or add-on is applied.
- A yellow warning banner appears in SharePoint indicating that data cannot be downloaded, printed, or synced.
- In Developer Tools (F12), the following error appears:
“Refused to execute script from '<URL>' because its MIME type ('text/html') is not executable, and strict MIME type checking is enabled.”
- The Portal Link Customizer (SPFx app) fails to load.
Users on managed devices do not encounter this issue. The SPFx app works as expected for them.
Cause:
This behavior is caused by Microsoft’s access policies for unmanaged devices.
When a user signs in to SharePoint from an unmanaged or non-compliant device, Microsoft 365 enforces restrictions that prevent SPFx (SharePoint Framework) apps from running.
As a result:
- The Mavim Portal Link Field Customizer cannot load.
- Other SharePoint, Teams, or Office client-side apps may also fail to work.
This is expected behavior defined by Microsoft security policy, not a defect in the Mavim app.
Solution / workaround:
This restriction is enforced by IT, cannot be worked around, and causes to disable all SharePoint, Teams, or Office integrated apps.
The following options are available:
- Use a managed or compliant device to access SharePoint.
- Ask your IT department to review and, if appropriate, adjust the unmanaged device access policy in Microsoft 365.
Additional information:
To configure the allowance of certain apps, see Microsoft’s official documentation:
https://learn.microsoft.com/en-us/sharepoint/control-access-from-unmanaged-devices
Notes:
- This behavior affects not only Mavim but all SPFx-based apps in SharePoint.
- It may also impact new apps being developed or tested within your organization.
Conclusion:
The Mavim Portal Link Field Customizer can only run on managed devices.
Unmanaged devices are restricted by Microsoft’s policies from running client-side (SPFx) apps in SharePoint for security reasons.
To use the feature, users must access SharePoint from a managed or compliant device.
