pluggable.php on line 1121

The secret is this:

output started at /customers/5/9/9/jazone.net/httpd.www/fiske/wp-config.php:1

That means! Look in wp-config.php on line #1, there’s a character there causing this. Basically it should be this:

<?php

and nothing else. If it is more, change it manually to JUST that ??

Now it says only <?php but still the same problem

I don’t know if that helps:
Had the same problem, after upgrading to 3.9 I had a blank screen when trying to reach the wp-admin and wp-login.php.
After disabling all plugins, and the theme, I had a message that said there said: Warning: Cannot modify header information – headers already sent by (output started at …..wp-config.php:26) ……wp-includes/pluggable.php on line 1121

solution:
OPEN wp-config.php – go to the line that indicates the problem(for me it was 26) make sure you delete every, white space, double empty spaces, double empty rows..
your wp-config.php should start without blank spaces with <?php
and end with ?>
without any empty rows or white spaces after that.
Hope that helps…

ralloux, big thanks for your help///

BIG THANK, man!

If you get this error and dont have any spaces or line breaks in wp-config.php outside <?php and ?>, check that the wp-cofig.php is saved as utf-8 without BOM

I vote for @andresxv answer. THAT is almost always the issue.

Thanks! ?? I also vote for @andresxv ??