This page is (hopefully) the beginning of a page to help resolve various technical difficulties with accessing or editing Wikipedia Pages.
A problem commonly reported by Microsoft Internet Explorer users relates to Wikipedia content that seems to be out-of-date. The problem usually manifests as disappearing page edits or days-old current events. This problem is almost always caused by browser caching. Almost all Web browsers temporarily store a copy of viewed Web pages on the user's computer, and almost all browsers are configured by default to display the cached copy if the user revisits the same page and it can be determined that the page has not been updated since his last visit. Usually, this process works as expected; however, some versions of Internet Explorer fail to always correctly re-download a page when it has become outdated (which may be a software bug).
(The Internet Explorer problem is not unique to Wikipedia; if you incorrectly see cached data here, you are probably seeing out-of-date pages on other sites too.)
There are three simple workarounds you should try if you encounter this problem.
Internet Explorer has been singled out in this troubleshooting section because the majority of cache-related problems are reported by Internet Explorer users, but similar issues could be found in other browsers (Netscape 7.2 had this problem). For more information about Wikipedia page caching and caching in general, see Wikipedia:Clear your cache.
Symptoms: Images don't show up correctly, or the 'Wikipedia' logo graphic appears instead of referenced images; log-in does not 'stick', and the user's ip keeps appearing at the top right of pages instead of the user name.
Apparently, Wikipedia must make use of some more advanced cookie features. Make sure that any Firewall or Privacy settings (e.g., ZoneAlarm, IE privacy settings, etc.) let Wikipedia have more freedom to set cookies as it desires; in particular, for ZoneAlarm settings, you must allow cookies with private header information.
Symptoms: Some contributors occasionally see error messages like the following instead of the page they requested:
Warning: open(/tmp/sess_e3b9b5e8f5afa9cce2aa0066fca4a143, O_RDWR) failed: Too many open files in system (23) in /usr/local/apache/htdocs/w/wiki.phtml on line 7
Warning: Failed opening 'Setup.php' for inclusion (include_path='.:/usr/local/lib/php') in /usr/local/apache/htdocs/w/wiki.phtml on line 12
Fatal error: Undefined class name 'outputpage' in /usr/local/apache/htdocs/w/wiki.phtml on line 14
Warning: open(/tmp/sess_e3b9b5e8f5afa9cce2aa0066fca4a143, O_RDWR) failed: Too many open files in system (23) in Unknown on line 0
Warning: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0
This is caused by the existence of a limit on the number of files which can be open at once, and at times too many users have been connected at once (essentially, this is Wikipedia becoming a victim of its own success). The limit has recently been increased to avoid this error occurring so frequently. However, some people's systems may have cached versions of the error message and so be continually redisplaying it; see "Cache Problems with IE" above.
The Firefox browser allows you to control whether Web pages can load images from outside the Web site you are viewing. If you enable this feature, images will not be displayed in Wikipedia pages, because images are loaded from upload.wikimedia.org rather than the en.wikipedia.org site you are viewing.
Alternatively, if you still wish to have this option on for other websites, you can leave the "for the originating web site only" checkbox checked, click Exceptions, and then add en.wikipedia.org and upload.wikimedia.org to the allow list.
As of Firefox 43.0.x, there is no "Load Images" checkbox, and the browser does not load any thumbnails for any media across any page of Wikipedia.
Back in 2005, with MediaWiki 1.4rc1, it was reported that sometimes, if one viewed the history of an article that was edited when the system was very busy, several of the most-recent edits ceased to be listed. If that happened, selecting either a different history length (e.g. "last 20" instead of the default 50) would re-enable the correct history to be shown. It seems to be a caching problem, not some problem with the database.
I have a new problem that is not on this list. What should I do?
See also Wikipedia:Browser notes.