
Can someone help me with the cause of this issue?
Could you please check the JSON content that you have put in the message part of the action card.
I guess while passing the image URI there will be a parameter "image src=" after the src there will be path to the image that you have put in the adaptive card
Could you please check the value present after the src the image has to be followed with a forward slash, if there is a back ward slash it will cause the error.
If this information helps you, please consider giving a thumbs up and mark the solution as resolved.