Instagram has strict guidelines when it comes to image aspect ratios.
Specifically, aspect ratios need to be between 0.8 and 1.91 for w:h.
Previously, images that didn't fall into these strict guidelines could not be posted and would result in a notification being sent to your phone or email.
Today, we built in a feature that automatically adds a white background to images with improper aspect ratios to simplify direct publishing.
Images that are too tall or too wide will now have a small white background added for Instagram publishing.
No additional work is needed from you - this new feature is automatically turned on for your account.