# Apache Server Frequently Asked Questions

$Revision: 1.8 $ ($Date: 2001/02/28 03:35:59 $)

The latest version of this FAQ is always available from the main Apache web site, at <`http://www.apache.org/docs/misc/FAQ.html`>.

If you are reading a text-only version of this FAQ, you may find numbers enclosed in brackets (such as "[12]"). These refer to the list of reference URLs to be found at the end of the document. These references do not appear, and are not needed, for the hypertext version.

## The Questions

1. Error Log Messages and Problems Starting Apache
   1. Why do I get "`setgid: Invalid argument`" at startup?
   2. Why am I getting "`httpd: could not set socket option TCP_NODELAY`" in my error log?
   3. Why am I getting "`connection reset by peer`" in my error log?
   4. The errorlog says Apache dumped core, but where's the dump file?
   5. When I run it under Linux I get "shmget: function not found", what should I do?
   6. Server hangs, or fails to start, and/or error log fills with "`fcntl: F_SETLKW: No record locks available`" or similar messages
   7. Why am I getting "`Expected </Directory> but saw </Directory>`" when I try to start Apache?
   8. I'm using RedHat Linux and I have problems with httpd dying randomly or not restarting properly
   9. I upgraded from an Apache version earlier than 1.2.0 and suddenly I have problems with Apache dying randomly or not restarting properly
   10. When I try to start Apache from a DOS window, I get a message like "`Cannot determine host name. Use ServerName directive to set it manually.`" What does this mean?
   11. When I try to start Apache for Windows, I get a message like "`Unable To Locate WS2_32.DLL...`". What should I do?
   12. Apache for Windows does not start. Error log contains this message "`[crit] (10045) The attempted operation is not supported for the type of object referenced: Parent: WSADuplicateSocket failed for socket ###`". What does this mean?

## The Answers

### D. Error Log Messages and Problems Starting Apache

1. Why do I get "`setgid: Invalid argument`" at startup?

   Your `Group` directive (probably in `conf/httpd.conf`) needs to name a group that actually exists in the `/etc/group` file (or your system's equivalent). This problem is also frequently seen when a negative number is used in the `Group` directive (e.g., "`Group #-1`"). Using a group name -- not group number -- found in your system's group database should solve this problem in all cases.

2. Why am I getting "`httpd: could not set socket option TCP_NODELAY`" in my error log?

   This message almost always indicates that the client disconnected before Apache reached the point of calling `setsockopt()` for the connection. It shouldn't occur for more than about 1% of the requests your server handles, and it's advisory only in any case.

3. Why am I getting "`connection reset by peer`" in my error log?

   This is a normal message and nothing about which to be alarmed. It simply means that the client canceled the connection before it had been completely set up - such as by the end-user pressing the "Stop" button. People's patience being what it is, sites with response-time problems or slow network links may experiences this more than high-capacity ones or those with large pipes to the network.

4. The errorlog says Apache dumped core, but where's the dump file?

   In Apache version 1.2, the error log message about dumped core includes the directory where the dump file should be located. However, many Unixes do not allow a process that has called `setuid()` to dump core for security reasons; the typical Apache setup has the server started as root to bind to port 80, after which it changes UIDs to a non-privileged user to serve requests.

   Dealing with this is extremely operating system-specific, and may require rebuilding your system kernel. Consult your operating system documentation or vendor for more information about whether your system does this and how to bypass it. If there is a documented way of bypassing it, it is recommended that you bypass it only for the `httpd` server process if possible.

   The canonical location for Apache's core-dump files is the ServerRoot directory. As of Apache version 1.3, the location can be set via the `CoreDumpDirectory` directive to a different directory. Make sure that this directory is writable by the user the server runs as (as opposed to the user the server is started as).

5. When I run it under Linux I get "shmget: function not found", what should I do?

   Your kernel has been built without SysV IPC support. You will have to rebuild the kernel with that support enabled (it's under the "General Setup" submenu). Documentation for kernel building is beyond the scope of this FAQ; you should consult the Kernel HOWTO, or the documentation provided with your distribution, or a Linux newsgroup/mailing list. As a last-resort workaround, you can comment out the `#define USE_SHMGET_SCOREBOARD` definition in the `LINUX` section of `src/conf.h` and rebuild the server (prior to 1.3b4, simply removing `#define HAVE_SHMGET` would have sufficed). This will produce a server which is slower and less reliable.

6. Server hangs, or fails to start, and/or error log fills with "`fcntl: F_SETLKW: No record locks available`" or similar messages

   These are symptoms of a fine locking problem, which usually means that the server is trying to use a synchronization file on an NFS filesystem.

   Because of its parallel-operation model, the Apache Web server needs to provide some form of synchronization when accessing certain resources. One of these synchronization methods involves taking out locks on a file, which means that the filesystem whereon the lockfile resides must support locking. In many cases this means it can't be kept on an NFS-mounted filesystem.

   To cause the Web server to work around the NFS locking limitations, include a line such as the following in your server configuration files:

     `LockFile /var/run/apache-lock`

   The directory should not be generally writable (e.g., don't use `/var/tmp`). See the `LockFile` documentation for more information.

7. Why am I getting "`Expected </Directory> but saw </Directory>`" when I try to start Apache?

   This is a known problem with certain versions of the AIX C compiler. IBM are working on a solution, and the issue is being tracked by problem report #2312.

8. I'm using RedHat Linux and I have problems with httpd dying randomly or not restarting properly

   RedHat Linux versions 4.x (and possibly earlier) RPMs contain various nasty scripts which do not stop or restart Apache properly. These can affect you even if you're not running the RedHat supplied RPMs.

   If you're using the default install then you're probably running Apache 1.1.3, which is outdated. From RedHat's ftp site you can pick up a more recent RPM for Apache 1.2.x. This will solve one of the problems.

   If you're using a custom built Apache rather than the RedHat RPMs then you should `rpm -e apache`. In particular you want the mildly broken `/etc/logrotate.d/apache` script to be removed, and you want the broken `/etc/rc.d/init.d/httpd` (or `httpd.init`) script to be removed. The latter is actually fixed by the apache-1.2.5 RPMs but if you're building your own Apache then you probably don't want the RedHat files.

   We can't stress enough how important it is for folks, especially vendors to follow the stopping Apache directions given in our documentation. In RedHat's defense, the broken scripts were necessary with Apache 1.1.x because the Linux support in 1.1.x was very poor, and there were various race conditions on all platforms. None of this should be necessary with Apache 1.2 and later.

9. I upgraded from an Apache version earlier than 1.2.0 and suddenly I have problems with Apache dying randomly or not restarting properly

   You should read the previous note about problems with RedHat installations. It is entirely likely that your installation has start/stop/restart scripts which were built for an earlier version of Apache. Versions earlier than 1.2.0 had various race conditions that made it necessary to use `kill -9` at times to take out all the httpd servers. But that should not be necessary any longer. You should follow the directions on how to stop and restart Apache.

   As of Apache 1.3 there is a script `src/support/apachectl` which, after a bit of customization, is suitable for starting, stopping, and restarting your server.

10. When I try to start Apache from a DOS window, I get a message like "`Cannot determine host name. Use ServerName directive to set it manually.`" What does this mean?

    It means what it says; the Apache software can't determine the hostname of your system. Edit your `conf\httpd.conf` file, look for the string "ServerName", and make sure there's an uncommented directive such as

      `ServerName localhost`

    or

      `ServerName www.foo.com`

    in the file. Correct it if there one there with wrong information, or add one if you don't already have one.

    Also, make sure that your Windows system has DNS enabled. See the TCP/IP setup component of the Networking or Internet Options control panel.

    After verifying that DNS is enabled and that you have a valid hostname in your `ServerName` directive, try to start the server again.

11. When I try to start Apache for Windows, I get a message like "`Unable To Locate WS2_32.DLL...`". What should I do?

    Short answer: You need to install Winsock 2, available from http://www.microsoft.com/windows95/downloads/

    Detailed answer: Prior to version 1.3.9, Apache for Windows used Winsock 1.1. Beginning with version 1.3.9, Apache began using Winsock 2 features (specifically, WSADuplicateSocket()). WS2_32.DLL implements the Winsock 2 API. Winsock 2 ships with Windows NT 4.0 and Windows 98. Some of the earlier releases of Windows 95 did not include Winsock 2.

12. Apache for Windows does not start. Error log contains this message: "`[crit] (10045) The attempted operation is not supported for the type of object referenced: Parent: WSADuplicateSocket failed for socket ###`". What does this mean?

    We have seen this problem when Apache is run on systems along with Virtual Private Networking clients like Aventail Connect. Aventail Connect is a Layered Service Provider (LSP) that inserts itself, as a "shim," between the Winsock 2 API and Window's native Winsock 2 implementation. The Aventail Connect shim does not implement WSADuplicateSocket, which is the cause of the failure.

    The shim is not unloaded when Aventail Connect is shut down. Once observed, the problem persists until the shim is either explicitly unloaded or the machine is rebooted. Instructions for temporarily removing the Aventail Connect V3.x shim can be found here: "How to Remove Aventail Connect v3.x from the LSP Order for Testing Purposes."

    Another potential solution (not tested) is to add `apache.exe` to the Aventail "Connect Exclusion List". See this link for details: "How to Add an Application to Aventail Connect's Application Exclusion List."