Hi,

Today we found a bug in our own Teams Bot using the Bot Framework where we couldn't Replace a previously sent message on mobile clients and an exception was throw (badRequest). (but we could for desktop clients without issues)

The root cause was the ReplyToId which was the string "0" on mobile clients (IOS & Android) but the value null on the Desktop Teams client, where we only checked for null in our code to not try to reply the message. So the bug was raised due to the inconsistency which I couldn't found documented somewhere.

I don't think this inconsistency is by design, so made this issue in the hope this could be aligned and bugs could be avoided in the future for other bot developers.

Wkr,
Jordy