How to fix microsoft outlook calendar forms issue

Question

Microsoft Forms box in outlook calendar says that to prevent malicious code from running, one or more objects in this form were not loaded. For more information, contact your administrator

Answer 1

@Keith Hassell said

Microsoft Forms box in outlook calendar says that to prevent malicious code from running, one or more objects in this form were not loaded.

If you are using the iCloud for Windows Classic Outlook Add-In (which installs custom Calendar forms), you have two choices:

1 -- Disable the iCloud Calendar Custom Forms:

See the Answer by "Sergio Iglesias Borrego Jan 9 2026" in
https://learn.microsoft.com/en-us/answers/questions/5694531/solved-outlook-classic-icloud-store-app-malicious

 2 -- Allow ActiveX Controls in Outlook Forms:

See the Answer by "Hornblower409 Jan 24 2026" in
https://learn.microsoft.com/en-us/answers/questions/5720294/outlook-one-or-more-objects-in-this-for-were-not-l

If you are not using iCloud for Windows, but some other custom Calendar forms. then option #2 is your only choice.

Answer 2

Dear @Keith Hassell

Thank you for providing the details. I understand that you’re seeing the message “To prevent malicious code from running, one or more objects in this form were not loaded” in the Outlook calendar.

To better narrow down the issue before suggesting troubleshooting steps, could you please clarify the following?

• Does this occur when creating a new calendar appointment, opening an existing appointment, or both?
• Is the message displayed for all calendar items or only specific appointments?
• Are you using Classic Outlook for Windows, and if so, which Outlook/Office version and build?
• Does this happen only with your main calendar, or also with shared/delegated calendars?
• Did this start recently, and was there any Office/Outlook update or configuration change before the issue began?
• Are you using any custom Outlook forms, templates, or third-party Outlook add-ins related to the calendar?

Once I have these details, I can narrow down whether this is related to a specific calendar item, Outlook configuration, or a custom form/component.