I got this error as well because the java jre path was removed or changed. The Java on my standalone dev Splunk server got updated by our SysAdmins and I was getting the "Can not communicate with task server, check your settings" error. It had been working just fine.
I went to settings and reviewed them. I verified the java path with what was on the server and sure enough the old java path was gone. I updated the java path to the new java path and saved. It attempted the restart of the task server but failed. I restarted splunk and everything came up working like normal.
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