Many customers experience Monitoring apps stop working after upgrade to Qlik Sense 3.0.x. The symptoms are Operations Monitor app and License Monitor app failed to reload in the Task view. Error messages can be found from the script logs, like "Error: QVX_UNEXPECTED_END_OF_DATA: Unexpected character encountered while parsing value: <. Path '', or "Error: Syntax error, missing/misplaced FROM:"
There have been bugs registered to address this issue, but currently the root cause is not clear yet.
Bug QLIK-64507 (the main one about this issue) was fixed in Qlik Sense 3.1 SR2: upgrading will probably solve the problem.
Otherwise, several things can be checked and changed to help to work around the issue:
1 - In a multi-node system there is additional configuration required for the data connections used by the Monitor Apps. Refer to http://help.qlik.com/en-US/sense/3.0/Subsystems/Monitoring/Content/Introduction/Monitor-Qlik-Sense-site.htm
2 - In a multi-node system, change URL of the "qrs_" REST data connections to point to the fully qualified domain name of the central node instead of to "localhost"
3 - Add RootAdmin role to the service account running the Qlik Sense services.
4.- If "Form" authentication is used in Virtual Proxy, the reload will fail. Create a separate Virtual Proxy that uses Windows authentication, and configure the URL in the REST data connections to use that Virtual Proxy.