Hey @sebastian k., thanks for the response.
When you say access the cookies from server side, is this from the applications that i'm testing with Synthetics or is this function within the Dynatrace portal?
this is the correct forum to post in and you correctly tagged it as 'Synthetic Monitors'. You can also add 'Synthetic Monitoring' so more people see it. I have added this.
I am not aware of a way to get the Cookie details on failure in Dynatrace Synthetic, assuming you don't also have RUM. This would make a great Product Idea. You can post them here and select 'Dynatrace Product Ideas' for the forum. Best wishes, Hannah