UserAgent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:50.0) Gecko/20100101 Firefox/50.0

Steps to reproduce the problem:
1. 
2. 
3. 

What is the expected behavior?
a

What went wrong?
ERR_SPDY_INADEQUATE_TRANSPORT_SECURITY

Did this work before? N/A 

Chrome version: <Copy from: 'about:version'>  Channel: n/a
OS Version: 6.1 (Windows 7, Windows Server 2008 R2)
Flash Version: Shockwave Flash 23.0 r0

no body knows the solution