WordPress Feed Issue: Blank line before XML declaration

Gosh! Yet another issue in my WordPress!

This is the third time in less than two weeks that I had to troubleshoot my installation of WordPress 2.5.

This time, however, the issue was not with WordPress itself, but this particular theme that I am using – Illacrimo. The feed for this blog was throwing an error:

I learned about the error when I tried to burn my feed through FeedBurner, which informed me that the feed (RSS XML) was not well-formed:

The URL you entered does not appear to be a valid feed. We encountered the following problem: Error on line 2: The processing instruction target matching “[xX][mM][lL]” is not allowed.

It directed me to Feed Validator to check the feed’s validity, and for sure it was not well formed:

line 1, column 1: Blank line before XML declaration

So what now? Google zindabad! On WordPress Support I found this and this, but I didn’t find any concise and to the point answer there.

I found a concise and workable solution on W3C’s site – check it out.

Why does this error occur?

If an XML declaration (<?xml ... ?>) appears in your feed, it must be the first thing in the feed, before any whitespace.

Unfortunately, with WordPress it seems all too easy for a plugin, a theme, or for your configuration file to contain a blank line. Further compounding this problem, some — but not all — feed readers compensate for this common error, allowing the error to go undetected for quite a while.

What’s the solution?

The solution is to trim/delete any blank lines outside of the <? ... ?> in the PHP code of either the theme files (functions.php) or WordPress files (wp-config.php, wp-rss2.php, wp-atom.php).

I had a blank line between two PHP code sections in the theme’s functions.php file. It was not evident at first, but thankfully, I finally got it to work! Now my feeds are working fine.

So go ahead and subscribe! :D


11 thoughts on “WordPress Feed Issue: Blank line before XML declaration

  1. El

    i do not use the default rss in wp… i just used the feedburner which works ok with me, but sometime slow update.

  2. El

    one more thing, i subscribe you rss for easy updates :) sorry for the so many comment, i hope i do not float in your blog :p

  3. Ash

    Thanks for the pointers. I’d left a blank line after the ?> tag in a plug-in I’d copy-pasted recently. So if you can’t find it anywhere else, think of what you recently installed.

  4. Thestef

    Thanks for the help, the RSS feed works again, the error occurred with a faulty plugin (bulk admin something), removed it and everything works again.

  5. Bri

    Yep, this took me ages and stumbled across your article. It was a line break in my functions.php between two blocks of also. Thanks.

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