One of the problems is Facebook app not installed and this same issue comes up when you try intsalling facebook messenger. The main cause is that when you upgrade to Nougat 7.0, the update automatically stores in-build apps signatures like facebook and messengers which blocks installation of new apps.
How To Fix App Not Installed On Facebook After Upgrading To Nougat
I have made my research on how to fix this after much research, i found out that the only way to fix this issues on nougat 7.0 is to hard reset your device after upgrading.
- Make sure you backup your device before starting the reset because you are going to losse everything on your device.
- Boot your phone to recovery mode by holding the power button and the vol + while the phone is off
- Now go to factory reset then go ahead wiping the device.
After doing these, try installing the new facebook messenger from playstore then see how it works.
To save you the stress of downloading both messenger and facebook apps together, download the facebook mod that has inbuilt messenger HERE