[wp-trac] [WordPress Trac] #27974: Unable to Log In, Cookies Are Blocked Due To Unexpected Output

[WordPress Trac]

#27974: Unable to Log In, Cookies Are Blocked Due To Unexpected Output
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 Reporter:  dejong1968              |       Owner:
     Type:  defect (bug)            |      Status:  new
 Priority:  normal                  |   Milestone:  Awaiting Review
Component:  Login and Registration  |     Version:  3.9
 Severity:  major                   |  Resolution:
 Keywords:                          |     Focuses:
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Comment (by SergeyBiryukov):

 > I read ticket #27373 where this is discussed, though the information
 shows no solution.

 I've outlined two possible reasons in that ticket:

 1. One of the active plugins (or the theme's `functions.php` file)
 produces unexpected output, causing a "headers already sent" warning and
 consequently preventing WordPress from setting the test cookie.
 2. [https://en.wikipedia.org/wiki/Byte_order_mark UTF-8 byte order mark]
 in `wp-config.php` (or theme's `functions.php` file) has the same effect
 as above.

 You should be able to find out the culprit by looking into server error
 logs.

 In case of a plugin issue, the solution would be to rename its folder via
 FTP. In case of a UTF-8 byte order mark issue, the solution is to re-save
 the file without it. [http://notepad-plus-plus.org/ Notepad++] has an
 option for that: "Convert to UTF-8 without BOM".

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Ticket URL: <https://core.trac.wordpress.org/ticket/27974#comment:3>
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