Warning: SimpleXMLElement::addAttribute() [simplexmlelement.addattribute]: Attribute already exists

I’ll be short on this one. For those of you in Magento theme developement, if you ever see this message

Warning: SimpleXMLElement::addAttribute() [simplexmlelement.addattribute]: Attribute already exists

Most likely you have layout problem. So dive into your theme /layout folder and quick check to see if it relly is the messed up layout in your theme is to rename entire /layout folder to something like /_layout. This way Magento will propagate to using default theme /layout folder. If the refresehed page now works, you located the error to be in /layout folder. Now do the same for few of the files inside the layout folder.

In my example I have added the following into catalog.xml under section

<remove name=”tags_popular” />

And that caused my Customer page to be broken after customer logs in.

Hope this help someone.