Frequently Asked Questions

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What do I do when I have problems?

Error Messages

What does this error message mean?

Support

• "Why can't I ...? Why won't ... work?" What to do in case of problems
• Whom do I contact for support?

"Why can't I ...? Why won't ... work?" What to do in case of problems

If you are having trouble with your Apache server software, you should take the following steps:

Check the errorlog!

Apache tries to be helpful when it encounters a problem. In many cases, it will provide some details by writing one or messages to the server error log. Sometimes this is enough for you to diagnose & fix the problem yourself (such as file permissions or the like). The default location of the error log is /usr/local/apache2/logs/error_log, but see the ErrorLog directive in your config files for the location on your server.

Check the FAQ!

The latest version of the Apache Frequently-Asked Questions list can always be found at the main Apache web site.

Check the Apache bug database

Most problems that get reported to The Apache Group are recorded in the bug database. Please check the existing reports, open and closed, before adding one. If you find that your issue has already been reported, please don't add a "me, too" report. If the original report isn't closed yet, we suggest that you check it periodically. You might also consider contacting the original submitter, because there may be an email exchange going on about the issue that isn't getting recorded in the database.

Ask in a user support forum

Apache has an active community of users who are willing to share their knowledge. Participating in this community is usually the best and fastest way to get answers to your questions and problems.

Users mailing list

USENET newsgroups:

• comp.infosystems.www.servers.unix [news] [google]
• comp.infosystems.www.servers.ms-windows [news] [google]
• comp.infosystems.www.authoring.cgi [news] [google]

If all else fails, report the problem in the bug database

If you've gone through those steps above that are appropriate and have obtained no relief, then please do let the httpd developers know about the problem by logging a bug report.

If your problem involves the server crashing and generating a core dump, please include a backtrace (if possible). As an example,

# cd ServerRoot
# dbx httpd core
(dbx) where

(Substitute the appropriate locations for your ServerRoot and your httpd and core files. You may have to use gdb instead of dbx.)

Whom do I contact for support?

With several million users and fewer than forty volunteer developers, we cannot provide personal support for Apache. For free support, we suggest participating in a user forum.

Professional, commercial support for Apache is available from a number of companies.

Error Messages

• Invalid argument: core_output_filter: writing data to the network

Invalid argument: core_output_filter: writing data to the network

Apache uses the sendfile syscall on platforms where it is available in order to speed sending of responses. Unfortunately, on some systems, Apache will detect the presence of sendfile at compile-time, even when it does not work properly. This happens most frequently when using network or other non-standard file-system.

Symptoms of this problem include the above message in the error log and zero-length responses to non-zero-sized files. The problem generally occurs only for static files, since dynamic content usually does not make use of sendfile.

To fix this problem, simply use the EnableSendfile directive to disable sendfile for all or part of your server. Also see the EnableMMAP, which can help with similar problems.