I tried to copy my artificer character and modify it but its infusions are not copied.

Then I tried to choose them from character editor but they are not displayed under equipments tab.

Then tried to choose them again but unexpected error happens and page reload doesn't help.

Do you own the Eberron book or was it being shared to you?

Hello! It is a known issue that infusions are not carried over when an Artificer is copied, and a ticket exists for the issue. :)

In order to get your infusions in equipment, you will first need to select your infusion options in the class portion of the character builder. 

If you continue facing issues in re-selecting your infusions on the class page, I would recommend sharing a link to your character.

Thank you!

I bought only subclasses

You didn't read the full description, didn't you? :D

I'm trying to select my infusion options in the class portion of the character builder but it doesn't work.

Quote from soso1234 >>

You didn't read the full description, didn't you? :D

I'm trying to select my infusion options in the class portion of the character builder but it doesn't work.

Quote from soso1234 >>

You didn't read the full description, didn't you? :D

I'm trying to select my infusion options in the class portion of the character builder but it doesn't work.

 Actually, it’s not clear from your first post that you tried in the builder. You explicitly mention the character sheet, and then talk abou “trying again,” but it’s not clear that that attempt was in the builder. In any event, I suggest you do what Millie requested and provide the url to the affected character. 

Quote from soso1234 >>

I bought only subclasses

 That should have been enough. Post the URL of the character.