Read the statement by Michael Teeuw here.
MMM-Remote-Control Error After Accessing From Browser After Installation
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 I just installed and configured the MMM-Remote-Control Module. I tried accessing it from my phone and from a different computer after I added the IP addresses to the whitelist. On both systems, I get the following error: {“status”:“error”,“reason”:“unknown_command”,“info”:“original input: {}”} That is the only line that shows up in the browser. Any advice? 
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 Hi schwarem, 
 Old post I know.
 Did you ever find a solution as I have the same problem?
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 @rudiau on your pi, by default, mm is set to NOT allow other system to access you need to change the mm config.js settings address:“0.0.0.0” 
 and
 ipWhitelist:[]to allow any system (computer, phone, tablet) on your local network 
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 Thanks for the reply Sam. 
 I had done that which you instruct.
 My problem, I just found, I had forgotten to add “.html” at the end as in “http//:192.168.xx.x:8080/remote.html” which threw this error message:- {“status”:“error”,“reason”:“unknown_command”,“info”:“original input: {}”}
 Thank you.
