Created attachment 372931 [details]
error message for invalid date range

The GnuCash attempts to get the transactions from the online bank even though the date range entered is incorrect.

Examples for incorrect user inputs:
1) "to"-date is smaller than "from"-date
2) "to"-date is in the future

In both cases GnuCash tries to get a connection to the online bank. It takes a while.
After that GnuCash shows an error message: "Error on executing job. Status: error - job contains errors". The error message is very general and does not say what is wrong.

It would be better to check the user inputs *before* the request will be send to
the bank, and to show a error message if the entered date range is wrong,
*without* creating the connection to the online bank.

examples error messages for invalid user data:
for (1): The date range is wrong. "To"-date cann't be smaller than the "from"-date.
for (2): The date range is wrong. "To"-date cann't be in the future. 

For more details see an image in attachment.