This article was created in response to a support issue logged with K2. The content may include typographical errors and may be revised at any time without notice This article is not considered official documentation for K2 software and is provided “as is” with no warranties.
You are unable to access K2 application components such as K2 Designer, K2 Workspace or K2 Management. This issue occurs due to the use of HTTP/2 in newer browsers, which has stricter requirements than HTTP/1.1. For more on HTTP/2, you can read the following Microsoft documentation: https://tools.ietf.org/html/rfc7540#page-5
You will see the following errors:
"ERR_SPDY_INADEQUATE_TRANSPORT_SECURITY" when using Chrome.
"NS_ERROR_NET_INADEQUATE_SECURITY" in Firefox.
This often occurs with the use of Windows 2016.
Although not a K2 issue, the errors caused by use of HTTP/2 can prevent usability of K2 components. Thus, this can be a crucial thing to check when coming across these types of errors.
This issue is primarily caused by incorrect ordering of blacklisted cipher suites. To re-order the cipher suites, you can download the IIS Crypto 2.0 tool here: https://www.nartac.com/Products/IISCrypto/Download
Once downloaded, you can refer to the following Microsoft documentation for steps on how to reorder blacklisted cipher suites to the bottom of your list: https://support.microsoft.com/en-us/help/4032720/how-to-deploy-custom-cipher-suite-ordering-in-windows-server-2016
You can find a complete list of blacklisted ciphers here: https://tools.ietf.org/html/rfc7540#appendix-A