I'm testing a newly created webpart locally using the gulp serve command after launching the gulp trust-dev-cert for certification installation, the local workbench opens up but all browsers are displaying the same error. Here's a screenshot from google chrome :

enter image description here

What I've tried :

  • Disabling firewall

I've googled and googled but with no success.

Does anyone have an idea about what's happening ?

  • definitely looks like a cert issue. Have you tried Fiddling? Or running trust-cert again? Nov 1, 2017 at 19:56
  • I've used Fiddler and it showed 200 http code. I've also removed the certificate using gulp "untrust-dev-cert" and reinstalled it again, no success.
    – KhalilG
    Nov 1, 2017 at 22:08

2 Answers 2


Try to give a look to the tip of Waldek Mastykarz if you are using latest LTS of Node.js here, it solved the issue for me (no need to disable firewall) : https://github.com/SharePoint/sp-dev-docs/issues/1002

  • Hi Patrick, thank you for your answer, it's working now. I've added a global environment variable like this : Key = "NODE_NO_HTTP2" and Value = "1". After that, we should close any command line or PowerShell session and restart again and it should be working.
    – KhalilG
    Nov 13, 2017 at 22:00

For Windows 10, Node version 8.9.1, SPFx version 1.4.0 below is the solution:

Add System variable

Control Panel -> System -> Advanced System Settings -> Environment Variables -> System Variables)

  • Variable name: NODE_NO_HTTP2
  • Variable value: 1

Don't forget to restart terminal.

  • These does not help in 2019. Look here for working solution: sharepoint.stackexchange.com/a/230115/5658
    – Gennady G
    Aug 6, 2019 at 15:04

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