tl;dr: Disable "Multiple HTTP commands (...)" under advanced settings
Lately I've been receiving a surge of an error with the following text:
You must provide a request body if you set ContentLength>0 or SendChunked==true. Do this by calling [Begin]GetRequestStream before [Begin]GetResponse.
If you're receiving this error while synchronizing please go to the GogTasks settings dialog, click Advanced and uncheck "Run multiple HTTP commands simultaneously".
I realize this is a workaround and not a fix from my side, but fixing it will cost more than it's worth at this point. You will only have a slight performance decrease in synchronzation.