The type or namespace name 'Http' does not exist in the namespace 'System.Net' (are you missing an assembly reference?) only onruntime

Question

this error apears only on run time not on build the build success

what is the yellow mark beside the reference mean

Answer 1

I have experienced this myself (the yellow), but no problem really occurred during execution. Anyways I have found some references of your problem here. The second most voted answer that includes Save, Clean and Rebuild solution seems appropriate.

Hope this helps you with your problem.