Why can't I sideload an old apk?

[littlenoodles]

can't sideload an old apk?

I installed the OTA update my Nexus 4, and it preserved everything there (except root) - including an older version of an app that I had emailed to myself as an APK from another device and loaded from my download folder (I prefer it to the current version).

But when I tried the 'add a user' feature, not all the apps were available, including that old app. Lollipop wouldn't let me install the APK as the new user, so I uninstalled the old app and installed the latest from Play. But I prefer the older version. So I tried uninstalling the latest version and re-installing the APK from my download folder. No dice. Does Lollipop have a problem with older APK's? I read somewhere that Android 5 expects apps to be signed differently than they used to be. Have I lost access to this older app for good?

 

[N4Newbie]

Re: can't sideload an old apk?

Do you have Lux installed? Apparently it causes a number of problems including - weird, I know - blocking the installation of sideloaded apps.

PS: I presume you have already gone to Settings -> Security -> Unknown sources...