In my server logs, I see the following line every second.
Jul 16 16:13:18 dmznyapig01 tyk-analytics: time=“Jul 16 16:13:18” level=error msg=“Session key not found” error=“redigo: nil returned”
Same - Just updated to the latest docker images from 2.6 gateway & portal 1.6.2 to gateway 2.7. portal 1.7 and this is non-stop in the dashboard log.
I think I found it. I had an old Tab open in my chrome browser that had an expired session. Once I found it and closed it, the error stopped.