I had Witcher 3 and completed this. Now I bought expansion pack and also got GOTY edition from gog.
I installed GOTY but after importing my old saves it says that "saves are not compatible".

Can anyone help with this?

PC or console?

Also, if you completed the game, what is the problem?

PC. I completed main game but now I want to complete DLC's, that's why I bought expansion pack :P

The DLCs are self-contained. You can start a new game and choose to play either one on its own from the startup menu. You will play in the same world if you play expansion only, but all the regular quests, main and otherwise, will be unavailable. None of them interact even if you play during a normal game. In other words, you don't need a saved game.

But I want to play with my leveled character. Which I cannot do without save.

That's not a problem either. Your character will automatically start at an appropriate level (32 for HoS and 34 for B&W). You will also automatically unlock the ability to start a New Game Plus game.

Nope. I cannot continue main game with my character and because game doesn't read properly my save then when I want to start DLC I get 34lvl character, but it's not my character.

You're being intentionally obstinate. It is Geralt. Geralt of Rivia. There is no "my character". When you play either of the expansions, they are separate from, and have no bearing on the main game. None of the actions and decisions you have made in prior games, or in the main campaign in this game make any difference, so your argument makes absolutely no sense.

Yeah it makes sense, because of equipment, skill tree, money etc. Just because it also "geralt" doesn't mean the bound between player and character is the same. Btw my character was near 40lvl.

There is a problem with saves, they doesn't work. I can play a game, but I didn't came here because I cannot play, I came here because of not working saves.

If you have no idea what to do then what's the point of your support? If I just would like to play DLC's then I know how to do it, but I want my saves! Here is a problem.

Then the game will be too easy. Just cheat (god mode). Because your saves are from a different version. Not the game's fault. Don't be an ass. I told you what to do.

I tried it on GOTY and non GOTY edition, if you mean by "different version" - patch then that might be the problem. Anyway it's not really fair towards players ;)

Anyway thank's for your time