Splunk Web UI is not coming up after upgrading Splunk

Applicability

Description

The following error shows up -

Waiting for web server at https://127.0.0.1:8000 to be available.........................................................
WARNING: Server Certificate Hostname Validation is disabled. Please see server.conf/[sslConfig]/cliVerifyServerName for details.

WARNING: web interface does not seem to be available!

Investigation

1) While checking the Search Head logs, observed the below INFO and WARN log-level messages: -

INFO UiHttpListener [13218 MainThread] - Shutting down webui
INFO UiHttpListener [13218 MainThread] - Shutting down webui completed
WARN SSLOptions [1591 WebuiStartup] - web.conf/[settings]/sslVersions: invalid value from system
INFO UiHttpListener [1591 WebuiStartup] - Server supporting SSL versions=
ERROR HTTPServer [1591 WebuiStartup] - Error setting up TLS, TLS will not be enabled. file=web Exception: No compatible SSL versions requested, can't set up SslContext

2) The issue with the Splunk Web UI appeared to be caused by the following WARN log-level message: -

WARN SSLOptions [1591 WebuiStartup] - web.conf/[settings]/sslVersions: invalid value from system

3) Upon checking further, under $SPLUNK_HOME/etc/system/local/web.conf file under the [settings] stanza, the following line is present:

[settings]
sslVersions = "tls"

Resolution

This format is incorrect due to the use of double quotes -  sslVersions = "tls"

The correct format should be - sslVersions = tls

Updated the parameter by removing the double quotes under the path $SPLUNK_HOME/etc/system/local/web.conf on the Search Head - 

[settings]
sslVersions = tls 

Related Links

Web Conf Spec Page