If a localizable message with spaces in the name (e.g. {{{button text}}}) is included in a banner, then the banner becomes uneditable through the CentralNotice interface, producing a fatal exception. Though documentation instructs to use hyphenated names, including spaces should either work or at least fail in a less confusing manner.
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[41e6ca5a] 2013-10-21 12:28:21: Fatal exception of type MWException
2013-10-21 15:30:55 mw1090 metawiki: [43570c48] /wiki/Special:CentralNoticeBanners/edit/B12_1026_US1_Jimmy Exception from line 1325 of /usr/local/apache/common-local/php-1.22wmf21/includes/HTMLForm.php: Invalid name 'wpmessage-button text' passed to HTMLFormField::__construct
#0 /usr/local/apache/common-local/php-1.22wmf21/extensions/CentralNotice/includes/HtmlFormElements/HTMLCentralNoticeBannerMessage.php(43): HTMLFormField->__construct(Array)
#1 /usr/local/apache/common-local/php-1.22wmf21/includes/HTMLForm.php(311): HTMLCentralNoticeBannerMessage->__construct(Array)
#2 /usr/local/apache/common-local/php-1.22wmf21/includes/HTMLForm.php(225): HTMLForm::loadInputFromParameters('message-button text', Array)
#3 /usr/local/apache/common-local/php-1.22wmf21/extensions/CentralNotice/special/SpecialCentralNoticeBanners.php(315): HTMLForm->__construct(Array, Object(RequestContext), 'centralnotice')
#4 /usr/local/apache/common-local/php-1.22wmf21/extensions/CentralNotice/special/SpecialCentralNoticeBanners.php(75): SpecialCentralNoticeBanners->showBannerEditor()
#5 /usr/local/apache/common-local/php-1.22wmf21/includes/SpecialPage.php(631): SpecialCentralNoticeBanners->execute('edit/B12_1026_US1_Jimmy')
#6 /usr/local/apache/common-local/php-1.22wmf21/includes/SpecialPageFactory.php(489): SpecialPage->run('edit/B12_1026_US1_Jimmy')
#7 /usr/local/apache/common-local/php-1.22wmf21/includes/Wiki.php(298): SpecialPageFactory::executePath(Object(Title), Object(RequestContext))
#8 /usr/local/apache/common-local/php-1.22wmf21/includes/Wiki.php(602): MediaWiki->performRequest()
#9 /usr/local/apache/common-local/php-1.22wmf21/includes/Wiki.php(467): MediaWiki->main()
#10 /usr/local/apache/common-local/php-1.22wmf21/index.php(49): MediaWiki->run()
#11 /usr/local/apache/common-local/w/index.php(3): require('/usr/local/apache/common-local/php-1.22wmf21/index.php')
#12 {main}
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**Version**: unspecified
**Severity**: major