Ultimaker 3 ext display shows build plate detected move outside of normal printer volume.

[Yuva 0]

Greetings....
I have been using Ultimaker 3 ext for the past 5 years.Now I have changed the original Olimex board from the printer.

After changing the board 50 mm gap was detected between the build plate and the nozzle. Active build plate calibration also done.Once manually calibrated display shows build plate detected move outside of the normal printer volume.

Kindly suggest the solution.

[Dustin 160]

Sounds like your running a olimex for a UM3 not UM3 Extended. 
https://support.ultimaker.com/s/article/1667417403337

[CarloK2 4]

To check the Olimex containing the correct model number: go into the maintenance menu and then the 'About this printer' screen. On the 3rd line it says "hardware type-id". For an UM3 that's 9066 or for an UM3-Extended it is 9511.

[gr5 2,235]

There is a way to switch the Olimex to the other type but it's not trivial.  You might want to ask ultimaker support for help in doing this or you could ship it back.