For better chat stability, go to Settings → Advanced → User Agent and set it to “Mobile” or “Android” (not Desktop).
To avoid being logged out or having an unverified session: facebook chat with opera mini verified
Facebook Chat on Opera Mini functioned on devices that could not support the native Facebook Messenger application. This included devices with as little as 1MB of RAM. This ubiquity established Facebook as the primary communication tool for a generation of first-time internet users in regions like Sub-Saharan Africa and Southeast Asia. For better chat stability, go to Settings →