For your internally developed enteprise app, the current best deployment approach is to use .pcg package because there are more precise control on version upgrade and deployment options (e.g. network restriction, deployment schedule, etc.).  There is also no need to upload the proprietary apk to Google's server, especially for company with worries about increased security risks on data leakage and app hacking when the app is not restricted to internal controlled environment.

Regarding I/O error, Matt has already listed out some of the possible causes.  Have you checked them out yet?

I would recommend using the Package builder to encapsulate the APK and install it via Profile to the device. This bypasses the Play Store architecture completely and allows you to install the APK directly onto the device from SOTI since their DPC is set to DO. 

thanks, but i tried building the package but it displays an I/O error, that´s why are trying to approve from the  application catalog, because it allows to install de apk. What can i do?

i´m using managed google in the add device rule

I/O error could imply there is a version of the app already installed on the device that would need to be uninstalled first. In that case you either didint increment the version of the new app when it was compiled or you signed it from a different machine and therefore SOTI isn't able to install it over the older version due to a signing mismatch. I suggest that you build a package that includes an pre-install script that uninstalls any previous manually installed versions that might be on the device and then 

I/O error could also mean that Google Play Protect is kicking in and is removing the app from the device. If that is the case you may want to understand why GPP doesn't like the app and work on addressing those issues so that the app isnt' inadvertently quarantined. 

Hi Xavier,

If the application is an in-house app, then I would suggest you go with Private apps:

Create an Application Catalog rule > Add > Managed Google Play applications > Managed Google Play > Click on Private Apps from the Left menu > Click on + sign on the bottom right of the window > Upload your APK and then get it approved. 

Thanks to all for your help, using the package builder was the best option to me, because of the deployment of my private app and to void GPP as Matt an Raymond tells. Also my I/O was an internal debug problem.

Thanks, i can add some private .apk, but they need to be developed as android tells, if the app developer omits any procedure , (developer name, debug build, etc.) it  can´t be uploaded.