Gprinter Mobile App upgrade to V5.0.4, Are you still using the old version?

Firstly, Let's check if you are using old version app:

Android Phone: Open App → Setting → Check Update → V5.0.4 

(congrats you are using the latest version Gprinter app already)

iOS Devices: Open App → Setting → Check Update → V1.0.0 

(congrats you are using the latest version Gprinter app already)

If you are using old version Gprinter app, feel free to update accordingly:

https://buying4u.blogspot.com/2020/03/gprinter-mobile-app-upgrade-to-v504-are.html