MediaWiki internal error.

Original exception: exception 'ErrorPageError' with message 'ページ名が未入力、無効、または正しくない言語間リンク・ウィキ間リンクです。ページ名に利用できない文字が含まれている可能性があります。' in /var/www/web4/html/includes/Wiki.php:178
Stack trace:
#0 /var/www/web4/html/includes/Wiki.php(59): MediaWiki->initializeSpecialCases(Object(Title), Object(OutputPage), Object(WebRequest))
#1 /var/www/web4/html/wiki(114): MediaWiki->initialize(Object(Title), NULL, Object(OutputPage), Object(User), Object(WebRequest))
#2 {main}

Exception caught inside exception handler: exception 'DBQueryError' with message 'A database error has occurred
Query: SELECT page_id,page_len,page_is_redirect FROM `wiki_jppage` WHERE page_namespace = '0' AND page_title = 'メインページ' LIMIT 1
Function: LinkCache::addLinkObj
Error: 1033 Incorrect information in file: './usr_web4_1/wiki_jppage.frm' (localhost)
' in /var/www/web4/html/includes/db/Database.php:636
Stack trace:
#0 /var/www/web4/html/includes/db/Database.php(591): Database->reportQueryError('Incorrect infor...', 1033, 'SELECT page_id...', 'LinkCache::addL...', false)
#1 /var/www/web4/html/includes/db/Database.php(1001): Database->query('SELECT page_id...', 'LinkCache::addL...')
#2 /var/www/web4/html/includes/db/Database.php(1081): Database->select('page', Array, Array, 'LinkCache::addL...', Array, Array)
#3 /var/www/web4/html/includes/LinkCache.php(167): Database->selectRow('page', Array, Array, 'LinkCache::addL...', Array)
#4 /var/www/web4/html/includes/Title.php(1886): LinkCache->addLinkObj(Object(Title))
#5 /var/www/web4/html/includes/Title.php(3124): Title->getArticleID()
#6 /var/www/web4/html/includes/Title.php(3177): Title->exists()
#7 /var/www/web4/html/includes/Linker.php(193): Title->isKnown()
#8 /var/www/web4/html/includes/Linker.php(445): Linker->link(Object(Title), '???????????????...', Array, Array)
#9 /var/www/web4/html/includes/OutputPage.php(1387): Linker->makeLinkObj(Object(Title))
#10 /var/www/web4/html/includes/OutputPage.php(1418): OutputPage->addReturnTo(Object(Title))
#11 /var/www/web4/html/includes/OutputPage.php(1082): OutputPage->returnToMain()
#12 [internal function]: OutputPage->showErrorPage('badtitle', 'badtitletext')
#13 /var/www/web4/html/includes/StubObject.php(58): call_user_func_array(Array, Array)
#14 /var/www/web4/html/includes/StubObject.php(76): StubObject->_call('showErrorPage', Array)
#15 [internal function]: StubObject->__call('showErrorPage', Array)
#16 /var/www/web4/html/includes/Exception.php(251): StubObject->showErrorPage('badtitle', 'badtitletext')
#17 /var/www/web4/html/includes/Exception.php(269): ErrorPageError->report()
#18 /var/www/web4/html/includes/Exception.php(327): wfReportException(Object(ErrorPageError))
#19 [internal function]: wfExceptionHandler(Object(ErrorPageError))
#20 {main}