Error 805a01f4 indicates an issue with your payment. Either your bank is not allowing the transaction to go through or Microsoft has detected suspicious activity on your account which is why it is return the error 805a01f4.
You may also get one of the following error codes (C101A007, C101A225, C101A249, C101C400, C101C401, C101C402, C101C403, C101C407 and C101C408)
Sometimes, the error code also comes up as a result of temporary glitch. Please follow all the methods listed below until the issue is fixed.
Method 1: Check Card Details
Make sure that the billing address on your windows phone billing account is same as the billing address your card is registered to. This can be verified by going to Account Settings on windowsphone.com. Click Sign in then Edit Payment Settings to confirm this. Make sure that the billing address is exactly the same on the Store as it is with your bank. You can also re-enter your card to confirm and ensure that is exact and correct. Once the information is updated, try again and if it still won’t work then call your bank to see if they are blocking it, they usually do this to prevent fraud. The number to call them is listed on the back of your card.
Method 2: Click Retry
Sometimes, if it is a temporary glitch with the servers, then click retry may also work.
Method 3: For Developers
If you are a developer, and the app had not been installed directly from the Windows store, then try changing the app guid to match the beta guid from the app store that was previously installed to the phone directly from the Store.