Piwiwk does not work anymore

There is an error. Please report the message (Piwik 2.8.1) and full backtrace in the Piwik forums (please do a Search first as it might have been reported already!).

Warning: preg_match(): Unknown modifier ‘a’ in /homepages/28/d314552651/htdocs/cmsanalytic/core/Url.php on line 270

Backtrace -->

#0 Piwik\Error::errorHandler(…) called at [:]
#1 preg_match(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/Url.php:270]
#2 Piwik\Url::isValidHost(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/Url.php:326]
#3 Piwik\Url::getHost(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/Url.php:372]
#4 Piwik\Url::getCurrentHost(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/Url.php:102]
#5 Piwik\Url::getCurrentUrlWithoutFileName(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/SettingsPiwik.php:170]
#6 Piwik\SettingsPiwik::getPiwikUrl(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/FrontController.php:404]
#7 Piwik\FrontController->init(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/dispatch.php:33]
#8 require_once(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/index.php:46]

here is an error. Please report the message (Piwik 2.8.1) and full backtrace in the Piwik forums (please do a Search first as it might have been reported already!).

Warning: preg_match(): Unknown modifier ‘a’ in /homepages/28/d314552651/htdocs/cmsanalytic/core/Url.php on line 270

Backtrace -->

#0 Piwik\Error::errorHandler(…) called at [:]
#1 preg_match(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/Url.php:270]
#2 Piwik\Url::isValidHost(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/Url.php:326]
#3 Piwik\Url::getHost(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/Url.php:372]
#4 Piwik\Url::getCurrentHost(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/Url.php:68]
#5 Piwik\Url::getCurrentUrl(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/FrontController.php:88]
#6 Piwik\FrontController->dispatch(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/core/dispatch.php:34]
#7 require_once(…) called at [/homepages/28/d314552651/htdocs/cmsanalytic/index.php:46]

When does that error occur. Did it occur right after the “autoupdate”?
Maybe reuploading the files of Piwik might help.

Hi there, if you can reproduce this error another time, please create an issue in github: Issues · matomo-org/piwik · GitHub

it did apear after i changed the trustes directory or url