Minecraft Forge does not start and the game crashes?

To
2

I have the problem that if I start Minecraft with Forge the following error message comes.

It looks like you're using an unsupported, modified version of the game.

The game crashed while initializing game.

Am

I need to be more specific.

But I guess you did not use the same version for everything.

Taking the same version in everything is very important.

To

So if I open the launcher everything is still normal but if I then press play on the game starts but then it crashes and then comes the error message oh yes and I have everything in the same version