Mashups not working after upgrade

[red_hawk78]

Hi we have recently upgraded our qliksense instance from sept 2018 to Feb 2020. Everything went smoothly but now our external web mashups wont work.

we get an error:

iisnode encountered an error when processing the request.

HRESULT: 0x6d
HTTP status: 500
HTTP subStatus: 1013
HTTP reason: Internal Server Error

You are receiving this HTTP 200 response because system.webServer/iisnode/@devErrorsEnabled configuration setting is 'true'.

In addition to the log of stdout and stderr of the node.exe process, consider using debugging and ETW traces to further diagnose the problem.

The last 64k of the output generated by the node.exe process to stderr is shown below:

Application has thrown an uncaught exception and is terminated:
SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>)
    at D:\OnDemandServices\qapmashup\qrs.js:28:27
    at IncomingMessage.<anonymous> (D:\OnDemandServices\qapmashup\qrs.js:132:20)
    at emitNone (events.js:111:20)
    at IncomingMessage.emit (events.js:208:7)
    at endReadableNT (_stream_readable.js:1064:12)
    at _combinedTickCallback (internal/process/next_tick.js:139:11)
    at process._tickCallback (internal/process/next_tick.js:181:9)

Has the upgrade changed a default settng?

Any ideas?