"Advanced Search..." leads to the initially described error

You can use the "Advanced Search...".

sorry to post on a closed item, but I just want to be sure:

There won't be a global search function anymore? You only can search 
via the search-field on the currently selected folder?

IMP 6.2.5

This only ever worked previously because there must have been a bug in 
Horde_Core's init code that was recently fixed.  Because accessing 
search page (or contacts page, for another example), which are basic 
pages, from a session marked as 'dynamic' should have ALWAYS triggered 
failure of the view verification check in IMP_Application#_init().

Not really going to spend any time tracking this down since basic view 
has been removed in 7.0 already.

Changes have been made in Git (FRAMEWORK_5_2):

commit 07502cefee9f78f035930d908cfb94b6ee6c68b3
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Mon Jan 5 19:07:48 2015 -0700

     Hotfix for #13773

     This is broken with current Horde_Core versions because recent changes
     to Horde_Core fixed a longstanding bug with initialization.

  imp/basic.php |    1 -
  1 files changed, 0 insertions(+), 1 deletions(-)

http://github.com/horde/horde/commit/07502cefee9f78f035930d908cfb94b6ee6c68b3

I can reproduce this when I select the 'Advanced Search...' option, 
the other search options are OK.

Downgrading Horde_Core to 2.17.2 fixed the issue for me.

I also get the behaviour shown in the screenshot and the error message 
when trying /imp/dynamic.php?page=search after applying the 
aforementioned updates. I'll try to roll back to the previous versions 
one by one and see what caused this problem.

the error occurs in dynamic view (basic works). The URL is generated 
by horde, when trying a GET with ?page=search in dynamic view, I get 
this error page:
Ein schwerer Fehler ist aufgetreten:
Page not found: search

The error occurs on two different sites, oviously after applying the 
following updates:
  Horde_ActiveSync 2.21.0 (stable) 2.23.0 (stable)
  Horde_Core       2.17.2 (stable) 2.18.0 (stable)
  Horde_Crypt      2.5.1 (stable)  2.5.2 (stable)
  Horde_Http       2.1.1 (stable)  2.1.2 (stable)
  Horde_Mime       2.6.0 (stable)  2.6.1 (stable)
  Horde_Prefs      2.7.0 (stable)  2.7.1 (stable)
  Horde_Util       2.5.1 (stable)  2.5.2 (stable)


Is there anything I can do to assist you in tracking down that error?

Can't reproduce.

Note that ?page=mailbox#search is not a valid URL.  The correct URL 
would be ?page=search.  So you need to figure out why that is 
happening on your system.

when choosing search, there's no search-panel opened anymore: the main 
imp-view is opened again instead (see attached picture).