Was that in the app its self? Because one of the things they told me to do after an update was to clear the cache partition in recover mode.

Turn phone off

Then hold the power-volume up-home

The phone will go into recovery mode

Then use the volume down to highlight clear cache partition Press power

Then volume down to say yes and press power again

The phone will then reboot in recovery mode then press power to reboot the phone

This will clear out all the old files that are left behind after an update

It will not change any of your settings on the phone

This partition is like a hard drive on a computer and holds all the old files

that your phone doesn't need anymore and some of these files can cause

conflicts with the new files but it is safe to clear this out after you get an update

Also have you gone to the play store and update all your apps?

Going from nougat to oreo they may all need to be updated