Troubleshooting .apk error "App Not Installed"

[Android Central Question]

It seems to be pretty common to have issues installing .apk files, although I'm not seeing my error addressed.

I loaded an .apk file straight from the developer. (It's not available on Google Play.) I've turned off app scanning, I've allowed for unknown sources (since I know the source, even if the phone doesn't). I can download and execute the .apk, I can even click install. The app runs to install and either ends in a second or ~20 seconds with the error "App Not Installed".

Everything I've read suggests I shouldn't be seeing this error, so I'm not sure what else to check. I'm pretty certain its the phone that isn't cooperating. I run Android 6.0 on a Galaxy S5. I've reached out to the developer to verify if my phone is simply not supported.

How do I otherwise identify this roadblock and how can I get past it?

 

[B. Diddy]

Welcome to Android Central! Has the developer gotten back to you yet? That would be my first guess (i.e., the phone or its Android version isn't compatible).

 

[ATX_Engr154]

Not yet. I'll see about sharing the response when they do. I'm afraid that may be the case. Unfortunately, that's the only reason that makes sense right now.