Officially global rom is not available. The last release was buggy enough that they had it pulled down 2 days after release. Many sellers who downloaded during that period quickly force flash the buggy rom and sell it as "global rom" units, which gave you that error message.

There is a workaround method suggested in xiaomi forum but it doesn't seem to last and message pop up again not long after.

Try this first and see if it removes the message:

Go to settings: System apps - Security - Disable "Allow internet connection".

Now go back and click onto Installed apps - Security - Clear Data

If it doesnt work then if u want to flash china rom, first apply to unlock bootloader, go download china stable rom and the necessary programmes on a windows pc. Once approval given then wait 72/360 hours before can flash. Fir the steps, u better check with miui forum

Really I tot Taiwan is remain on china rom.

How much for Redmi 5 plus 4/64 convert to RM?
Thanks

Then how?

Have to wipe and flash back to Chinese rom?

Return to directD, ask for a replacement with china stable rom.

just return it bro...otherwise the message will pop up until u cant tahan....

Should stay back on Chinese Rom..until they announced global rom for everyone.

nope....only testpoint / unlock bootloader 

I think you need to flash to the official ROM first.