User not appearing in impersonation

[alinatoc]

Whenever I impersonate a user, impersonation modal says "No matches found" but when I try to look for the user in System Security > Users and Groups > Users the user exists. I also ensured that this user is Active. Other reasons you can tell about why this happens?

Cheers,

Allen

[NikhilKumaK]

Hi @alinatoc 

Also, when 

Web service access only is checked then for that user; we can't impersonate it.