OK, you were wright, thanks. Anyway, I don't have any new message in addition of "A database query error has occurred. This may indicate a bug in the software."
Is it possible the update.php didn't run well : are there some new tables that should have been add in the wiki database ?
Here is the log for the update :
"Turning off Content Handler DB fields for this part of upgrade.
...have ipb_id field in ipblocks table.
...have ipb_expiry field in ipblocks table.
...already have interwiki table
...indexes seem up to 20031107 standards.
...have rc_type field in recentchanges table.
...index new_name_timestamp already set on recentchanges table.
...have user_real_name field in user table.
...querycache table already exists.
...objectcache table already exists.
...categorylinks table already exists.
...have pagelinks; skipping old links table updates
...il_from OK
...have rc_ip field in recentchanges table.
...index PRIMARY already set on image table.
...have rc_id field in recentchanges table.
...have rc_patrolled field in recentchanges table.
...logging table already exists.
...have user_token field in user table.
...have wl_notificationtimestamp field in watchlist table.
...watchlist talk page rows already present.
...user table does not contain user_emailauthenticationtimestamp field.
...page table already exists.
...have log_params field in logging table.
...logging table has correct log_title encoding.
...have ar_rev_id field in archive table.
...have page_len field in page table.
...revision table does not contain inverse_timestamp field.
...have rev_text_id field in revision table.
...have rev_deleted field in revision table.
...have img_width field in image table.
...have img_metadata field in image table.
...have user_email_token field in user table.
...have ar_text_id field in archive table.
...page_namespace is already a full int (int(11)).
...ar_namespace is already a full int (int(11)).
...rc_namespace is already a full int (int(11)).
...wl_namespace is already a full int (int(11)).
...qc_namespace is already a full int (int(11)).
...log_namespace is already a full int (int(11)).
...have img_media_type field in image table.
...already have pagelinks table.
...image table does not contain img_type field.
...already have unique user_name index.
...user_groups table exists and is in current format.
...have ss_total_pages field in site_stats table.
...user_newtalk table already exists.
...transcache table already exists.
...have iw_trans field in interwiki table.
...wl_notificationtimestamp is already nullable.
...index times already set on logging table.
...have ipb_range_start field in ipblocks table.
...no page_random rows needed to be set
...have user_registration field in user table.
...templatelinks table already exists
...externallinks table already exists.
...job table already exists.
...have ss_images field in site_stats table.
...langlinks table already exists.
...querycache_info table already exists.
...filearchive table already exists.
...have ipb_anon_only field in ipblocks table.
...index rc_ns_usertext already set on recentchanges table.
...index rc_user_text already set on recentchanges table.
...have user_newpass_time field in user table.
...redirect table already exists.
...querycachetwo table already exists.
...have ipb_enable_autoblock field in ipblocks table.
...index pl_namespace on table pagelinks includes field pl_from.
...index tl_namespace on table templatelinks includes field tl_from.
...index il_to on table imagelinks includes field il_from.
...have rc_old_len field in recentchanges table.
...have user_editcount field in user table.
...page_restrictions table already exists.
...have log_id field in logging table.
...have rev_parent_id field in revision table.
...have pr_id field in page_restrictions table.
...have rev_len field in revision table.
...have rc_deleted field in recentchanges table.
...have log_deleted field in logging table.
...have ar_deleted field in archive table.
...have ipb_deleted field in ipblocks table.
...have fa_deleted field in filearchive table.
...have ar_len field in archive table.
...have ipb_block_email field in ipblocks table.
...index cl_sortkey on table categorylinks includes field cl_from.
...have oi_metadata field in oldimage table.
...index usertext_timestamp already set on archive table.
...index img_usertext_timestamp already set on image table.
...index oi_usertext_timestamp already set on oldimage table.
...have ar_page_id field in archive table.
...have img_sha1 field in image table.
...protected_titles table already exists.
...have ipb_by_text field in ipblocks table.
...page_props table already exists.
...updatelog table already exists.
...category table already exists.
...category table already populated.
...have ar_parent_id field in archive table.
...have user_last_timestamp field in user_newtalk table.
...protected_titles table has correct pt_title encoding.
...have ss_active_users field in site_stats table.
...ss_active_users user count set...
...have ipb_allow_usertalk field in ipblocks table.
...pl_namespace, tl_namespace, il_to indices are already UNIQUE.
...change_tag table already exists.
...tag_summary table already exists.
...valid_tag table already exists.
...user_properties table already exists.
...log_search table already exists.
...have log_user_text field in logging table.
...l10n_cache table already exists.
...index ls_field_val already set on log_search table.
...index change_tag_rc_tag already set on change_tag table.
...have rd_interwiki field in redirect table.
...transcache tc_time already converted.
...*_mime_minor fields are already long enough.
...iwlinks table already exists.
...index iwl_prefix_title_from already set on iwlinks table.
...have ul_value field in updatelog table.
...have iw_api field in interwiki table.
...iwl_prefix key doesn't exist.
...have cl_collation field in categorylinks table.
...categorylinks up-to-date.
...module_deps table already exists.
...ar_page_revid key doesn't exist.
...index ar_revid already set on archive table.
...ll_lang is up-to-date.
...user_last_timestamp is already nullable.
...index user_email already set on user table.
...up_property in table user_properties already modified by patch patch-up_property.sql.
...uploadstash table already exists.
...user_former_groups table already exists.
...index type_action already set on logging table.
...have rev_sha1 field in revision table.
...batch conversion of user_options: nothing to migrate. done.
...user table does not contain user_options field.
...have ar_sha1 field in archive table.
...index page_redirect_namespace_len already set on page table.
...have us_chunk_inx field in uploadstash table.
...have job_timestamp field in job table.
...index page_user_timestamp already set on revision table.
...have ipb_parent_block_id field in ipblocks table.
...index ipb_parent_block_id already set on ipblocks table.
...category table does not contain cat_hidden field.
...have rev_content_format field in revision table.
...have rev_content_model field in revision table.
...have ar_content_format field in archive table.
...have ar_content_model field in archive table.
...have page_content_model field in page table.
Content Handler DB fields should be usable now.
...site_stats table does not contain ss_admins field.
...recentchanges table does not contain rc_moved_to_title field.
...sites table already exists.
...have fa_sha1 field in filearchive table.
...have job_token field in job table.
...have job_attempts field in job table.
...have us_props field in uploadstash table.
...ug_group in table user_groups already modified by patch patch-ug_group-length-increase-255.sql.
...ufg_group in table user_former_groups already modified by patch patch-ufg_group-length-increase-255.sql.
...index pp_propname_page already set on page_props table.
...index img_media_mime already set on image table.
...iwl_prefix_title_from index is already non-UNIQUE.
...index iwl_prefix_from_title already set on iwlinks table.
...have ar_id field in archive table.
...have el_id field in externallinks table.
...have rc_source field in recentchanges table.
...index log_user_text_type_time already set on logging table.
...index log_user_text_time already set on logging table.
...have page_links_updated field in page table.
...have user_password_expires field in user table.
...have pp_sortkey field in page_props table.
...recentchanges table does not contain rc_cur_time field.
...index wl_user_notificationtimestamp already set on watchlist table.
...have page_lang field in page table.
...have pl_from_namespace field in pagelinks table.
...have tl_from_namespace field in templatelinks table.
...have il_from_namespace field in imagelinks table.
...img_major_mime in table image already modified by patch patch-img_major_mime-chemical.sql.
...oi_major_mime in table oldimage already modified by patch patch-oi_major_mime-chemical.sql.
...fa_major_mime in table filearchive already modified by patch patch-fa_major_mime-chemical.sql.
...user_id is already unsigned int.
...rc_comment in table recentchanges already modified by patch patch-editsummary-length.sql.
...hitcounter doesn't exist.
...site_stats table does not contain ss_total_views field.
...page table does not contain page_counter field.
...msg_resource_links doesn't exist.
...msg_resource doesn't exist.
...bot_passwords table already exists.
...have wl_id field in watchlist table.
...cl_collation key doesn't exist.
...index cl_collation_ext already set on categorylinks table.
...collations up-to-date.
...site_stats is populated...done.
Purging caches...done."