Upload Error - Cannot upload apk file to Google Play Developer Console?
The problem is solved. It seems to be caused by some cookies etc. I have tried uploading my apk in browser's incognito mode and had success.
Cookies are the most general problem creators for every scenarios.
If you cleared that while using any kind of log-in and log-out credentials.
It is working well.
Otherwise,please use all time"Incognito private browsing window" that problem can't occurs anymore.
For some reason Firefox seems to be particularly badly behaved with the Google Play Console - even the main account page times out and sits there forever, displaying the spinner. My solution to not being able to upload an APK was to close the tab on Firefox and use another browser (Safari). Upload worked very quickly and was available to release within seconds.