While updating task T218184 I'm not able to edit 'Description' and browser leads me to,
The webpage at https://phabricator.wikimedia.org/maniphest/task/edit/218184/ might be temporarily down or it may have moved permanently to a new web address.
ERR_SPDY_PROTOCOL_ERROR
Adding comment to that task works!
(Not able to upload screenshot too!)
Quoting @Tgr from T108449#1839934:
ERR_SPDY_PROTOCOL_ERROR is a very generic error message that basically means something went wrong with the communication with the web server while using SPDY o HTTP/2. That could be a browser bug, an Apache or Varnish bug, a web server configuration problem, whatever.
If the error still occurs and you can reproduce it with some reliability, I think the way forward is to log the network details as described here and file a bug with those details attached against the Chromium project; they can at least figure out what the exact protocol problem is.
Quoting @CDanis from T213214#4870225:
If you can manage to reproduce this consistently, even for a few minutes, capturing a Chrome NetLog using chrome://net-export would probably shed light on what is happening.
https://dev.chromium.org/for-testers/providing-network-details
Details on what is captured and how to use it are at https://www.chromium.org/developers/design-documents/network-stack/netlog
It looks like that this issue has been resolved and I'm able to edit description of T218184 now!