Continuing the discussion from Error 500 when trying to flash Raspberry Pi 3:
I have a RPi 2 B, and this is still happening — firmware target set to 0.5.1-pi.11, latest particle-agent, system is up to date (apt-get update/upgrade), fresh reboot, I2C enabled. Using the SparkFun BME280 library, which doesn't seem to have any weird dependencies. Works fine with a super simple app that doesn't use I2C. As soon as I2C is called in the app, I instantly see "Error 500" when trying to flash. What exactly does 500 mean in this context? Is there any way to be provided more specific error messages?