HTTP2 compatibility layer tries to write the header multiple times.

[StephenLynx]

I was given this bug report:

https://i.imgur.com/YcJtGBJ.png

Yes, I was given just an image.

The issue is: this very same code runs smooth as butter for 4 years now on sites with great amounts of traffic and writing headers twice was NEVER and issue. The same poster said the person that he contacted insisted the issue was with my software. I'd ask you to look at this issue again, is not the first time my software stumbles with issues on the compatibility module. The moment this user changed from the http2 to the http module, the issue disappeared.

[StephenLynx]

Update: just now I realized the user said he was running node 12.0.0. I have another user that I asked to run with node 12.7. Will keep you posted if this second user also finds any issue.