Hello.
So, I want to get the Undefined block in Scratch 3.0, but not the Red Hat block. Is this possible? If so, how do you get it?

when green flag clicked
wait () secs

you might want to search it up on Bing

you might want to search it up on Bing

I did, but I still couldn't find the answer.
Google Search

what do you mean undefined? you mean this?

... :: grey 

it's not there in normal scratch

Make a custom block named Undefined.

Add the block that calls Undefined to your project, then drag it into the backpack.

Now delete the call and the block from your project.

You can then drag the call to the Undefined block from the backpack back into your project.
It will not create a new Hat block for Undefined.

The red hat block has essentially replaced the undefined block in Scratch 3.0, so you can't.

what do you mean undefined? you mean this?

. . .

it's not there in normal scratch

No, I mean like this:

undefined

Make a custom block named Undefined.

Add the block that calls Undefined to your project, then drag it into the backpack.

Now delete the call and the block from your project.

You can then drag the call to the Undefined block from the backpack back into your project.
It will not create a new Hat block for Undefined.

I tried, but it wouldn't work.

when green flag clicked
undefined

The red “undefined” block does not exist in Scratch 3.0, only in 2.0.

Do you mean this one?
(obtained this by uploading the color fx test block from v349, which we have access to):

If so, you can't because 3.0 deletes all undefined blocks (including the “obsolete!” one).