Error notice vs upgrade banner

We have two distinct styles for the following:

• An error message (which is a red/black banner at the top of the page)
• An upgrade message (which is a light-colored banner prompting the user to upgrade their plan)

We are restricting video uploads to users on a Free plan. When they attempt to upload, we inform them that this is only possible when they upgrade their plan.

In this case, which prompt should we use? An error message prompting them to upgrade, or a basic upgrade message? I was thinking about the latter so it isn't so scary for the user.