Minecraft Bedrock: Unable to connect to world?

I just wanted to play a relaxed game of Minecraft Bedrock with my friend, he on the tablet, me on the laptop. We're both logged into Minecraft and the world we want to play in (it is saved on his tablet) is also shown to me as normal. When I click on it, it loads briefly, but then the message always comes: Unable to connect to world. (as seen in the picture below).

What can I do so that this doesn't happen and I can play Minecraft with my friend as normal and why does this even happen?

Thanks for all helpful answers!

Albert.

It is possible that he is playing in a different version than yours. You could check out.