I was getting the same error and I believe your're right Serkan.
In the Server itself I cannot open the "Select File". If I access it through my Google Chrome Browser in my windows 10 laptop I can do it really fast.
Hope that Hui Ming marks your answer as Correct.
thanks for your help,
but I am using IE 11 on Windows 10, it was suppose to be supported.
BTW I have gotten a response from qlik support:
1. The problem that you are experiencing might be related to bug: QLIK-76520, please see the description below for more details.
2. The only workaround is to use a different browser
Guess I will have to wait for the next release for them to fix this issue.