"Sorry, that test location already has too many tests pending" - but not running any

I’ve upgraded webpagetest and wptagent with today’s versions from gihub (running them both on Ubuntu 16.04).

I think I didn’t set up everything properly, as when I’m trying to start a new test, web interface just displays “Sorry, that test location already has too many tests pending. Pleasy try again later.”.

There aren’t any tests running, so that’s a surprise.

wptagent is polling /work/getwork.php and is receiving HTTP 200.

/var/www/webpagetest/logs/ does not contain any logs (does webpagetest write any logs anywhere?).

Apache error log does not log any errors.

How can I debug this?

I am also facing similar issue after upgrading the server to latest version ( .
My Agents are on windows 7.

After upgrading my old Agents (I had 6 agents earlier) are running. I added 2 more agents. Everything Ok Only I am not seeing the CPU Utilization for the new Agents in “http://URL/getTesters.php

When I am trying run a test it is giving the below message.
“Sorry, that test location already has too many tests pending. Pleasy try again later.”

I have had the same issue arise, but changed nothing. Tests were running on pre-determined schedule and now they the server just returns this error. The problem is persistent after a reboot so am at a loss as to what has happened.

I have changed nothing Basically my private instance is now down and some real help as to how to fix this would be appreciated

Update after some investigation - resolved

Ok - so relying on WPT issued messages may not be a good thing. The basic message states that the location is already running too many tests, but this is just a default message that is issued if the test cannot be added. A quick look in the logs shows that the server was space constrained so a quick delete of the previous results followed by another reboot has cleared this condition.
Hope this helps others as a potential check if you come across the same message.