Why are resource constrained devices unable to parse responses from my Heroku app?

Issue

I use hardware devices to interact with my Heroku app. When the routing layer is upgraded to Router 2.0, I noticed the devices no longer can parse the responses.

Resolution

Some libraries for resource constrained hardware devices have limited buffer space for response headers. With Router 2.0 generating longer network error logging related response headers than the legacy router, the total size of response headers may exceed the fixed size of the buffer and the devices may experience difficulty in parsing responses as expected.

Please double check the size limit of your library for response headers and compare it with the actual response headers. To reduce the size for response headers, it is possible to remove the NEL related response headers for the app. Please refer to the KB article How do I remove NEL related response headers from my Heroku app?