Copilot on Mac will not accept jpg or png ?

Microsoft 365 Copilot image upload support depends on both the Copilot experience and the account type.

From the provided information:

• The free Copilot experience at copilot.microsoft.com supports image upload (PNG, JPEG, etc.) as described in File upload in Microsoft Copilot.
• For Microsoft 365 Copilot (work or school), image formats such as .png, .jpg, .jpeg, .gif, .bmp, .tiff are explicitly listed as supported for “Understand, analyze, and change images.”
• A Microsoft Q&A thread confirms that, for Microsoft 365 Copilot Chat at m365.cloud.microsoft, image upload currently works only with work/school accounts. Personal Microsoft 365 Family/Premium accounts cannot upload or paste images there and receive a “file type is not supported” message.

Given that behavior, the Mac M365 Copilot app is following the same limitation: with a personal Microsoft 365 subscription, image upload in Microsoft 365 Copilot Chat (including the Mac app) is not enabled, so JPG/PNG are rejected even though PDF works. That is why image files work in the browser in some Copilot experiences but not in the Microsoft 365 Copilot app tied to the M365 environment.

There is no client-side fix (conversion, drag-and-drop, etc.) that will bypass this; enabling image upload in Microsoft 365 Copilot Chat for personal accounts would require a change on the service side. For now, the options are:

• Use the free Copilot experience described in File upload in Microsoft Copilot, which supports image upload for PNG/JPEG.
• Or use a work/school Microsoft 365 account with Microsoft 365 Copilot, where image formats are supported for “Understand, analyze, and change images.”

References:

• File upload in Microsoft Copilot
• File formats supported by Microsoft 365 Copilot
• Microsoft 365 Copilot Chat on m365.cloud.microsoft does not allow image uploads or image paste - Microsoft Q&A