You may also want to check your proxy settings.
I had the same error message as soon as I login to Splunk.
When I looked into web_service.log, I saw the following error message.
startup:96 - Unable to read in product version information; (403, 'Forbidden')
The root cause is that I have set the http(s)_proxy environment variable (as I'm inside a proxied environment) and Splunk seem to have issues connecting to that proxy to read in product version info. After I have reset the http(s)_proxy variable to empty strings, the issue no longer exists.
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