UPDATE We have managed to fix this by manually patching the framework file after build. See this post for more info. Reference patching tool can be found at https://github.com/SWAG-MASHA/UnityWebRequestWebPatcher --- We're experiencing a strange issue sending POST request in certain browsers on certain machines. The request body seems to be completely mangled (looks like random bytes of memory) We haven't been able to find the culprit of the problem - it's relatively rare (it only happens on most browsers of 4 of the machines of our QA department and 1 browser of our developer). But even 3% reproduce-ability among our players means a lot of negative feedback, so we can't leave it as it is. We tried updating to the latest 2018.4.19, but it doesn't solve the problem I can't really find any info on these Unity forums or on the internet and can't file a bug because we don't have a 100% working way of reproducing it. Does anyone have any info regarding this? Or anyone experiencing something similar?