'Invalid json' when trying release 0.3.0 with example input file

[misterkevinski]

Unfortunately I get this error message 'You have submitted an invalid json!' (see in Figure 1) when trying the optimisation tool with the example input file from Getting Started page.

Figure 1: Error message at the frontend web gui

I am using release 0.3.3 of the backend and release 0.3.0 of the frontend service. When tring it with frontend release 0.1.0 it is accepted but frontend can not communicate with the backend service then.

Here is the example json file:
example.zip