The hostname sent by the client or browser via Server Name Indication (SNI) does not match the request host header. It is commonly caused by the following:

  • your local browser setting the incorrect SNI host header
  • a network proxying SSL traffic caused a mismatch between SNI and the Host header of the request.


Step 1

Test for an SNI mismatch via an online tool such as: SSL Shopper.

Step 2

Provide Cloudflare Support the following information:

  • A HAR file captured while duplicating the error