A problem that has recently been plaguing users is one that might seem devastating, but actually can be resolved quite easily. Experienced users might know how to fix the error, but there are many Android owners who are stumped. Fear not, here is how to solve ''unknown error 961''.
When downloading an app, either free or paid, sometimes there’s a problem when installing due to ''unknown error 961''. Don’t panic! First, in order not to lose any money if it's a paid app, ask for a refund immediately, which you can do within 15 minutes just by selecting the repayment option in the Google Play Store. If you need extra help with this, we’ve written a tutorial on how to try paid apps for free. After this is done, you need to get down to solving the issue itself
1) To do this, go into your phone’s settings, then Applications (or Apps or Application Manager), swipe to the left to ''All'' and scroll down until you find Google Play, tap on it.
2) In the app information page, tap on the button to empty the cache.
3) If this doesn't solve the problem, try to delete the data from the Play Store which is found on the same page (Settings > Manage applications > Google Play > Delete data). This was how I was able to download and install the app when faced with the error 961 message. Hopefully this post will help you in future!
I hope this helped you solve the problem. Let us know in the comment below.
Source :- androidpit