[Grammar] How can't you do that? VS. How can you not do that?

[sky3120]

How can't you do that? VS. How can you not do that?

Both are possible and they mean the same?

Thank you so much as usual.

 

[Rover_KE]

First, let's get the question right, sky:

'Are they both possible and do they mean the same?'

Only the second is natural.

Rover

 

[BobK]

They mean the same. The first is informal (and plain unacceptable in some circles ;-))

b