Facebook has changed the dimensions of flash players embedded in the news feed from 460 by 460 pixels to 398 by 398 pixels. Facebook initially labeled the change a bug that would be fixed, but later made the change official. The new dimensions may cause some flash to be displayed improperly, so developers should check to ensure their flash attachments look right.

The dimension change was not on the developer roadmap (that we are aware of), and so may have caught many developers by surprise. Facebook recently implemented a new monthly migration system for allowing developers to integrate new features and bug fixes to the platform at the their own pace. The system was designed to make it easier for developers to handle these types of changes, but only works if the changes are in the roadmap.

The bug which initially caused the size change was reported on November 3rd. It retroactively changed the size of all flash players embedded in the news feed from 460 pixels to 398. The next day, Facebook engineer Mike Vernal confirmed on the bug report’s comment reel that developers should “operate under the assumption that that is a bug that we will be fixing shortly.” Four days later, though, the bug was not fixed and Facebook staffer Jeff Bowen asked developers for examples of malfunctioning flash players. Then two days later, Douglas Purdy, Facebook’s new Director of Developer Relations reversed Facebook’s position, explaining that “moving forward the size will be 398×398, but that size is subject to change (and your content will be scaled accordingly).”

The changed appeared at the same time that Facebook altered the format of stories in the news feed by reducing the text size and showing status updates or context for rich shares below a user’s name instead of on the same line. It is possible that Facebook was testing the new format which caused the bug, and when it decided to implement the new format the bug was simply accepted and labeled “WONTFIX.”

The back and forth on the decision further angered some developers, especially those with embeds including non-vector graphics which don’t scale properly. Facebook has worked hard to communicate platform changes lately, but that didn’t happen here.