HTTP2 post request in pycurl - nginx

Question

I am trying to hit a nginx server that is behind an alb. I am triggering a simple HTTP2 POST request using pycurl. My request looks like this'
import io
import pycurl
curl = pycurl.Curl()
curl.setopt(curl.URL, "https://alb-xxxx.us-east-1.elb.amazonaws.com/endpoint")
curl.setopt(pycurl.HTTP_VERSION, pycurl.CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE)
curl.setopt(pycurl.POST, 1)
curl.setopt(pycurl.VERBOSE, 1)
curl.setopt(pycurl.SSL_VERIFYPEER, 0)
curl.setopt(pycurl.SSL_VERIFYHOST, 0)
with io.BytesIO() as buf:
curl.setopt(curl.WRITEFUNCTION, buf.write)
curl.perform()
print(buf.getvalue())
curl.close()
The error i am getting is
error Traceback (most recent call last)
<ipython-input-91-0756005b6c1b> in <module>()
16 with io.BytesIO() as buf:
17 curl.setopt(curl.WRITEFUNCTION, buf.write)
---> 18 curl.perform()
19 print(buf.getvalue())
20 curl.close()
error: (92, 'HTTP/2 stream 1 was not closed cleanly: INTERNAL_ERROR (err 2)')
the error occurrence is random. some times I get correct response and sometimes I get error like this. But when I try to do the same in curl I am getting correct response always. This is my curl command.
curl -v -k --http2-prior-knowledge -X POST https://alb-xxx.us-east-1.elb.amazonaws.com/endpoint
My post request response is a string({"field":"value"}). My NGINX configuration file looks like this
location =/endpoint {
if ($request_method = POST) {
return 200 '{"field":"value"}';
}
}
I don't know why I am getting correct response in curl but getting a different response in pycurl. Am I doing anything wrong in pycurl ?
Pycurl version -> 7.43.0.6
Python version -> 3.8.5
Thanks. Any help is appreciated.