Without any info about your project and what you're doing there as well as possibly other info on render settings, your system and so on we can't tell you why this error may come up. The first thing to do would be to check for effects like Motion Tile with excessive values that can indeed expand the buffer size beyond acceptable limits. Anything more will require proper info.
Several effects artificially increase the frame size. Grow Bounds and Motion Tile are just two. It is easy to exceed the limit if you have not adequately designed your workflow. If you upload a screenshot showing the modified properties of the layers and a Flow Chart if you have a lot of nested comps, we can probably point you in the right direction. Often the fix is as simple as pre-composing, turning off collapse transformations, or reducing the value of a property.