The solution from fernandomaroto works and fixed it, solved.
Thanks :)

@joekamprad No, “Options button > Preferences” does nothing, no password prompt, no error message. The preferences window appears only if pamac is run with sudo.

@joekamprad Thanks,
Now gksu is installed, but the problem persists :(
After hitting “commit” button the error window appears.

Hi,

Everytime i run pacmac-manager (not as root) and try to install a package from AUR, after pressing ‘Commit’ a window apperars showing only the message “Authentication failed”.

I think its something broken after an update.

There is no output on the terminal. System is up-to-date.
Window manager is I3.

Any help will be apreciated.
Thanks