Mobile App Dev

Android: INSTALL_FAILED_UPDATE_INCOMPATIBLE

I keep running into this issue about once a month. I build and deploy my app to my Android device, and at the end of deployment I get the ambiguous error:

INSTALL_FAILED_UPDATE_INCOMPATIBLE

This thread in the Xamarin forums gives a variety of different solutions, but I wanted to document it for myself and others in a nice clear list of things to try, in the order of easy-to-do first:

Uninstall whatever version of your app is on the device and try to deploy again.
Install the app store version of your app, uninstall it, and try to deploy again.
In the system Settings/Device/Applications/App Manager on the All tab, find the

com.<appname>.<anypackage>

Select it, uninstall it, and then try to deploy again.

This third one is sure-fire way, so you might start with that and skip the trial and error.

Xamarin iOS Certificate Issues

Several times now I’ve encountered issues where Xamarin doesn’t let me deploy an app under development to an iOS device. In some cases, I’ve found the answer here, but I’m going to lay out the full solution for all cases.

Register your unique device ID (UDID) at Apple Developer Device List. You won’t have to start here every time. In fact, if you’ve been developing/deploying to your device for a while and Xamarin suddenly stops deploying to the device, this is not the problem. But if you’ve never used the device for development before, this is where you have to start. You can search for instructions on getting your UDID, but it seems the easiest way is to connect your device and view it in iTunes.
Run Xcode and refresh your certificates. Often times, an Xcode update will require user intervention to accept the Terms of Use, etc. or enter a password to complete installation of the update. That may be all you have to do. But if your certificate has expired or you’ve updated the device list in step 1, you’ll have to download the cert again. In Xcode v7 (it has changed over time and probably will again) choose the menu options: Xcode > Preferences > Accounts > [Team Name] > View Details > Download All.
In Xamarin Studio v5, go to the context menu for your iOS project and select: Options > iOS Bundle Signing. You may have to twiddle with the Signing Identity and the Provisioning Profile. In my case, they were both set to Automatic after a XS update, but to get it to work I had to change the Provisioning Profile to iOS Team Provisioning Profile.