This is a Copy of
FS#2070, because the fix described there (invalidating the cache) did not fix the problem for me.
After upgrading my wiki from 2009-12-25c to 2010-11-07, I get the following warning on the first load on most pages:
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Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'Doku_Renderer_metadata::section_edit' was given in /var/www/dokuwiki/inc/parserutils.php on line 419
Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'Doku_Renderer_xhtml::section_edit' was given in /var/www/dokuwiki/inc/parserutils.php on line 555
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This indeed seems to be related to the cache, as hitting reload makes the warning disappear for the loaded page. HOWEVER: The warnings reappear every time a page is recached. After invalidating the cache (touch conf/local.php), the warning reappears on (first load of) all pages. It also appears immediately after saving changes to a page (since it is recached at that moment, I would presume).