INSTALL_FAILED_UPDATE_INCOMPATIBLE shows up even after the original is completely removed
I am trying to install a modified apk file onto my Nook Simple Touch. I modified the Reader.apk program, recompiled it, and signed it with my own key.
I know that you cannot install an app over a current app if the signing keys are different. However, I am getting the error INSTALL_FAILED_UPDATE_INCOMPATIBLE even after completely uninstalling the original Reader.apk app.
After checking the packages.xml file, I removed the entry for the old Reader.apk app. And I am still getting this error. The app is completely uninstalled, and I cannot install my modified version.
Even signing the original sources with my new key causes this error to come up (so it has nothing to do with the actual changes I made).
Answer
According to the docs, this error appears "if a previously installed package of the same name has a different signature than the new package (and the old package's data was not removed)."
If you're sure you removed it, there may be some spot where the old signature is still floating around that removal didn't, um, remove. Wiping the emulator/device data should clear up the problem.