I had this error today and it was indeed linked to a cache containing 
an earlier version of the "form_sections.js" file.

In my case it was due to the mod_cache apache module and to resolve 
the problem I added in the right place a "CacheDisable /horde" 
directive in the apache config.

I hope this can guide other people.

This doesn't make any sense. Have you been updating from an earlier 
version without restarting the browser? Did you empty the browser cache?

This is Iceweasel 2.0.0.15



Mozilla/5.0 (X11; U; Linux i686; de; rv:1.8.1.15) Gecko/20080612 
Iceweasel/2.0.0.15 (Debian-2.0.0.15-0etch1)

What browser is this?

Yes, there is a message in the error console of firefox, it seems to 
be webmail related



Fehler: null has no properties

Quelldatei: http://mail.oneport.de/js/form_sections.js

Zeile: 31



(Translation: Fehler -> Error, Quelldatei: Sourcefile, Zeile -> Line)



I'm a little bit confused, since js/form_sections.js has just one line:



karl-heinz:/var/www/pages/mail.oneport.de # wc -l js/form_sections.js

0 js/form_sections.js



karl-heinz:/var/www/pages/mail.oneport.de # cat js/form_sections.js

function Horde_Form_Sections(B,C){this._instanceName=B;var 
A,D;this.toggle=function(E){if(!document.getElementById){return 
false}openSectionId=this._get();D=document.getElementById(this._instanceName+"_section_"+openSectionId);if(D){D.style.display="none";document.getElementById(this._instanceName+"_tab_"+openSectionId).className=null}D=document.getElementById(this._instanceName+"_section_"+E);if(D){D.style.display="";document.getElementById(this._instanceName+"_tab_"+E).className="activeTab"}this._set(E)};this._get=function(){return this._openSection};this._set=function(F){var E=document.getElementById(this._instanceName);if(E!=null&&typeof 
E.__formOpenSection!="undefined"){E.__formOpenSection.value=escape(F)}this._openSection=F};this._set(C)};

Are there javascript errors? What are they?

using Administration/Setup/Horde only the "General" tab ist usable, 
clicking on "Database", "Authentication" and so on has no effect. 
Nothing is loaded.

Same with other applications.