Today I decided to migrate from a workaround I was using to the AvatarUrl feature.
I stumbled upon this error/limitation of 200 characters per URL.
"UpdateAvatarUrl: error InvalidParams message Invalid input parameters details {ImageUrl:[ImageUrl cannot exceed 200 characters]}"
Please update the API doc page.
And can you make the limit more flexible, some facebook profile picture URLs are longer than 200 characters, I have at least one failing with 201 characters!