Here's additional information on 500 Internal server error with 6.4 Release:
HTTPS_PROXY in splunk-launch.conf causes 500 Internal Server Error after login. To work around this issue:
Option 1: Export the following setting into your environment prior to starting Splunk Enterprise: NO_PROXY="127.0.0.1,localhost"
or add it to $SPLUNK_HOME/etc/splunk-launch.conf and restart Splunk Enterprise.
Option 2: Unset the proxy on the Linux system and restart Splunk Enterprise:
If the proxy is set in splunk-launch.conf but is not actually used or needed, remove the setting and restart.
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