I'm afraid it is currently not possible to upload an avatar for rooms, only for users and the group account itself. This is known requested feature, but I can't confirm if it will be available soon. Although feel free to vote and comment for it at:
We've partnered with Slack and are working with them to build a migration program to help customers easily make the move based on our announcement here. Your investment in business communications and modern teamwork experience will continue to reap benefits on Slack.
Our customer service and support team are here to help you through this transition if your group wants to. To learn more about next steps and other information, please read more on our Migration Hub.
Due to this partnership, we will only be fixing critical bugs in HipChat and Stride. This means new features won't be added to the product.
Let me know if you have additional questions.
...from the beginning. We have built up a lot of content in HipChat, with it being a core tool in our distributed company model. While it is true that we didn’t need to move to Slack immediately, we felt it...
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