When Google updated Calendar to version 5.1 last week, it introduced a bug that hit users with an "unable to launch event" message whenever they tried to launch an APK downloaded using Chrome or the stock Android browser. Now the company has pushed out a hotfix update intended to do away with the problem.
This bug prevented some users from launching the apps they downloaded in our APK download posts, but we were able to get around this issue by rolling out a server tweak for APK Mirror. Nevertheless, many other sources remained afflicted, and this was hardly a solution to the broader problem affecting numerous Android users.
Google's pushing out the fix now, but if you want to try your hand at installing it manually, I know a place that will hook you up.
The APK is signed by Google and upgrades your existing app. The cryptographic signature guarantees that the file is safe to install and was not tampered with in any way. Rather than wait for Google to push this download to your devices, which can take days, download and install it just like any other APK.
File name: com.google.android.calendar-5.1-1768105-2015020931-minAPI16.apk
Version: 5.1-1768105 (2015020931) (Android 4.1+)