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Cannot login PRTG on android 6.0 (using QR code)



I'm having trouble when I tried to connect the app to my account using QR code. It returned an error "Invalid JSON result". I also tried login manually but it also return the same error or "I could not retrieve the passhash. Perhaps your password is wrong". The info entered were 100% correct. I read around this KB and tried all answer but still failed.

I'm using Android 6.0, running PRTG v17.3.32.2478 and this is the first time I tried to use PRTG for android.

The error: Invalid JSON result {"NewMessages":"0", "NewAlarms":"0", "Alarms":"1", "PartialAlarms":"", "AckAlarms":"", ...

and bunch other stuffs in the JSON.

prtg prtg-for-android qr-code

Created on Sep 14, 2017 7:09:15 AM

3 Replies



Dear mtluthfi,

Thank you very much for your knowledge base post.

Please contact us directly via email to [email protected], because we'll need some more information which are better provided by email.
Please refer to this knowledge base thread, so the case will be assigned to me.

Best regards,

Created on Sep 14, 2017 1:18:19 PM by  Sebastian Kniege [Paessler Support]



I have started receiving the same error when trying to log into the Android app:

Invalid JSON result: top.location.href='/Main_login.asp';

PRTG version: Android app: 20.0.0

If I try the demo app, I get the message:

I could not retrieve the passhash. Perhaps your password is wrong?

But I'm not asked for a username/password.

I have noticed the after the first failed attempt, I was retrying and getting the same message regarding the password. I finally noticed that after the first failed attempt, all data is kept in the fields, however the protocol is not saved and changes to HTTP. Changing it back to HTTPS results in the first error message again, but again, the protocol is not saved, yet all other information is.

This isn't critical for me since I just use this on my server at home, but it would be nice to get it working again.

Thank you.

Created on Mar 29, 2020 5:31:33 PM



Hi Marc,

Please check whether this approach helps to solve the issue with the error code could not retrieve the passhash.

Assuming that your mobile reaches your PRTG Core Server, you can easily connect the PRTG mobile app with your Core Server by scanning the QR code that can be found in PRTG's web interface under "Setup | Account Settings \ My Account".
Click on "Show QR code for Mobile App Login" to reveal the QR code and scan it within the PRTG for mobile app. This QR codes will automatically link all required information for the referring user account.


Created on Mar 30, 2020 1:17:47 PM by  Sebastian Kniege [Paessler Support]

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.