It seems like there are two problems going on here:
1.) The whitespace at the top. I'm still suspicious that this is related to Thomas' problem -- whitespace after a "?>" in some file somewhere (VuFind loads a lot of files, so these things can be hard to track down -- that's why VuFind 2 is not going to have any closing ?> tags anywhere... it's legal and prevents this specific problem). I definitely recommend giving one more look to any files you have customized to make sure there is no unexpected whitespace at the end... or simply eliminate the ?> at the bottom to avoid future problems.
2.) Even if you fix the whitespace problem, it looks like you're still going to have problems, because the generated XML has no items in it. Perhaps this is somehow related to the whitespace problem, but it might also mean that some customization you have made is conflicting with the XSL transformation that generates the RSS. It might be worth looking at the XML prior to transformation to see if data is obviously missing. I can point you to the code if you haven't already found it -- let me know if you need more details.
> -----Original Message-----
> From: Evelyn Weiser [mailto:weiser@...]
> Sent: Thursday, November 15, 2012 10:17 AM
> To: vufind-general@...
> Subject: [VuFind-General] RSS feed error
> Hi everyone,
> we are having a problem with our RSS feed. We get the
> following error message:
> error on line 2 at column 6: XML declaration allowed only
> at the start of the document
> Below is a rendering of the page up to the first error.
> Thomas Misilo wrote about this very same issue in April
> this year . Unfortunately Demian's answer did not help
> us solve the problem.
> I checked Thomas' catalogue  and the RSS feed seems to
> be working fine, so there must be a solution... Could
> anyone give us a hint?
> Thanks very much in advance
>  https://catalog.lib.fit.edu/
> Evelyn Weiser
> Universitaetsbibliothek Leipzig
> Projekt finc
> Beethovenstraße 6
> 04107 Leipzig
> fon: +49 (0)341 9730510
> mail: weiser@...
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