Error:

There are too many errors in your work.

I get an error message when I try to log in.

Fault: 

His greatest fault is that he talks too much.

It's all your fault  

Flaw:

The diamond had a flaw that affected its clarity.

Despite its beauty, the painting had a small flaw in the corner.

Flawless

Her English isalmost flawless.

Spot:

There's a spot on your shirt."

She noticed a small spot of ink on her notebook.

There's a spot on the mirror; I'll clean it later.

Spotless:

The kitchen was spotless after she finished cleaning.

He has a spotless record so far.