Support » Fixing WordPress » “invalid RSS feed” intermittently

  • Readers who subscribe to my main RSS feed, for example from Thunderbird, report “invalid RSS feed”. Worse yet, the problem comes and goes.

    I used to check my feed and SOMETIMES it reports two blank lines at the top. Whitespace isn’t allowed before the “<?xml version…” tag and some readers (like perhaps Tbird) barf.

    Feedvalidator gives helpful info about themes and plugins being likely sources of spurious empty lines, but I can’t find the offenders.

    The key point to this is that the problem is INTERMITTENT. Oft times it works, but I’ve seen it fail several times.

    Any suggestions on how to locate the source of this problem? Anyone else seen it?

Viewing 8 replies - 1 through 8 (of 8 total)
  • Moderator Samuel Wood (Otto)

    (@otto42) Admin

    Well, giving us a link to the feed in question would probably be the most helpful…

    Okay, here ’tis: feed://

    I deliberately omitted this from the initial post, because I’m requesting help with a methodology more than direct intervention. But any assistance is welcomed.

    press on!

    Moderator Samuel Wood (Otto)

    (@otto42) Admin

    Hmm.. Well, I’m not seeing any blank lines on either the feed or the main site.

    The intermittent problems are the hardest to diagnose. What you need to figure out is what is the common factor. When does it get the blank lines in the feed? When you know that, you’ll know more specifically where to look.

    Thanks Otto.

    Like I tried to say in the initial problem statement: it’s intermittent and primarily seen with Thunderbird. (I see from stats that you used Firefox 2.0.0, and no one has reported a problem with that.) feedvalidator comments indicate that some RSS readers may strip whitespace at the top of an RSS feed (Firefox could be one that does). So you may have encountered the whitespace and still not have encountered the “invalid feed” error.

    What I’m really looking for is a methodology to troubleshoot why the RSS feed varies over time: what you called “the common factor”.

    I tried restarting Apache to see if it’s related to the initial run of some code – no luck. I disabled cache to see if that behaves differently – no luck. I pruned blank lines out of some home grown plugins (and checked the others for blank lines) – no luck.

    I use wp-cache plugin, which appears to cache RSS feed as well as other pages. Unless I’m mistaken, sometimes the cached results include spurious whitespace and sometimes not. That baffles me completely.

    I tried switching cache off (and clearing the cache) but couldn’t determine a pattern. The problem behavior is too rare to see a pattern yet.

    Any suggestions about what to ask the user or what “wires to jiggle” to try to reproduce and isolate this behavior? Thanks in advance.

    Anyone ever seen “invalid RSS feed” from Thunderbird on another WordPress site?

    press on!

    Moderator Samuel Wood (Otto)

    (@otto42) Admin

    So you may have encountered the whitespace and still not have encountered the “invalid feed” error.

    No. If I saw the whitespace, then it would be in the source of the returned data, regardless of what the resulting page looked like.

    The client is irrelevant, the data would be the same either way. Yes, an RSS reader might ignore the whitespace, but I did not use an RSS reader to look at it.

    Okay, I agree that “view source” for the RSS page is a good way to observe the presence or absence of the white space in the feed. Thanks for your attention on this.

    I’m still stuck with a sneaky intermittent problem and the old adage that “absence of evidence is not evidence of absence”. I’ll wait for more reports to roll in and look for patterns.

    press on!

    when clicking on the RSS on my blog I get this message:

    Redirect Loop
    Firefox has detected that the server is redirecting the request for this address in a way that will never complete.

    What would be the most common fix for this?

    I’m interested in finding out more about how to solve this problem, because it’s been a recurring question over on the forums for some time. Users (including myself) have reported that they’re seeing this error when trying to use drupal’s aggregator on WordPress-generated feeds:

    The feed from [insert sitename here] seems to be broken, due to an error “Invalid document end” on line 1.

    jbenni’s report of two blank lines at the top sounds like it could be related.

    (The thread on )

    The solution some users have found is to add the problematic feed to Feedburner and use the resulting feed. Apparently feedburner’s pretty fault-tolerant, and it returns a feed minus the mysterious error.

    Two wordpress feeds I’ve encountered that are subject to the intermittent error are and

Viewing 8 replies - 1 through 8 (of 8 total)
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