Troubleshooting Oracle HTTP Server

This appendix describes common problems that you might encounter when using Oracle HTTP Server (OHS), and explains how to solve them. It includes the following topics:

Oracle HTTP Server Unable to Start Due to Port Conflict

You can get the following error if Oracle HTTP Server cannot start due to port conflict:

[VirtualHost: main] (98)Address already in use: make_sock: could not bind to address [::]:7777


Determine what process is already using that port, and then either change the IP:port address of Oracle HTTP Server or the port of the conflicting process.


If the OHS instance was created with the config Wizard, there is no automated port management. It is possible to create multiple instances using the same Listen port.

System Overloaded by Number of httpd Processes

When too many httpd processes run on a system, the response time degrades because there are insufficient resources for normal processing.


Lower the value of MaxRequestWorkers to a value the machine can accommodate.

Permission Denied When Starting Oracle HTTP Server On a Port Below 1024

You will get the following error if you try to start Oracle HTTP Server on a port below 1024:

[VirtualHost: main] (13)Permission denied: make_sock: could not bind to address [::]:443

Oracle HTTP Server will not start on ports below 1024 because root privileges are needed to bind these ports.


Follow the steps in Starting Oracle HTTP Server Instances on a Privileged Port (UNIX Only) to start Oracle HTTP Server on a Privileged Port.

Using Log Files to Locate Errors

You can use the following log files to help locate errors:

Rewrite Log

This log file is necessary for debugging when mod_rewrite is used. The log file produces a detailed analysis of how the rewriting engine transforms requests. The value of the LogLevel directive controls the level of detail.

Script Log

This log file enables you to record the input to and output from the CGI scripts. This should only be used in testing, and not for production servers.

See Also:

ScriptLog in the Apache HTTP Server documentation at:

Error Log

This log file records overall server problems. Refer to Managing Oracle HTTP Server Logs for details on configuring and viewing error logs.

Recovering an OHS Instance on a Remote Host

If you need to recover an Oracle HTTP Server instance that is installed on a remote host (that is, a host with just managed servers but no Administration Server), you must use tar and untar; and do not work in this scenario.

Oracle HTTP Server Performance Issues

The following are performance issues, along with their solutions, that you might encounter when running Oracle HTTP Server:

Special Runtime Files Reside on a Network File System

Oracle HTTP Server uses locks for its internal processing, which in turn use lock files. These files are created dynamically when the lock is created and are accessed every time the lock is taken or released. If these files reside on a slower file system (for example, network file system), then there could be severe performance degradation. To counter this issue:

On Linux:

In httpd.conf, change Mutex fnctl:fileloc default to Mutex sysvsem default where fileloc is the value of the directive LockFile (two places).

On Solaris:

In httpd.conf, change Mutex fnctl:fileloc default to Mutex pthread default where fileloc is the value of the directive LockFile (two places).

UNIX Sockets on a Network File System

The mod_cgid module is not enabled by default. If enabled, this module uses UNIX sockets internally. If UNIX sockets reside on a slower file system (for example, network file system), a severe performance degradation could be observed. You can set the following directive to avoid the issue:

  • If mod_cgid is enabled, use the ScriptSock directive to place mod_cgid's UNIX socket on a local filesystem.

DocumentRoot on a Slow File System

If you are using mod_wl_ohs to route the requests to back-end WLS server/cluster, and the DocumentRoot is on a slower file system (for example, network file system), then every request that mod_wl_ohs routes to the backend server can experience performance issues. This can be overcome by setting WLSRequest to ON instead of SetHandler weblogic-handler.

Out of DMS Shared Memory

In some extreme configurations, you might see the following message in the OHS error log:

dms_fail_shm_expansion: out of DMS shared memory in pid XXX, disabling DMS; increase DMSProcSharedMem directive from YYY

This is because of an incorrect calculation of required shared memory for OHS DMS. This can be resolved by setting DMSProcSharedMem to a larger value than the default of 4096. Continue setting DMSProcSharedMem 50% higher until the problem is resolved. The minimum value for DMSProcSharedMem is 256 and the maximum value is 65536.

In a configuration with a very large number of virtual hosts (hundreds or thousands), if the above workaround does not work, you can instead, set the environment variable OHS_DMS_BLOCKSIZE to a large enough value that Oracle HTTP Server starts without error. The value of this variable is in kilobytes and a value of 524288 is a good starting point. If the error persists, continue to increase the value by 50% until Oracle HTTP Server starts without error.

Performance Issues with Instances Created on Shared File Systems

If you encounter functional or performance issues when creating an Oracle HTTP Server instance on a shared filesystem, including NFS (Network File System), it might be due to filesystem accesses in the default configuration. In this case, you must update the httpd.conf file specific to your operating systems. For information on updating the this file, see Updating Oracle HTTP Server Component Configurations on a Shared Filesystem.

Node Manager 12c (12.1.2) OHS Throws Java Exception on AIX

When running Oracle HTTP Server on AIX, if ULIMIT values of file handlers are small, Node Manager console/log throws" error=24, Too many open files" error on AIX.


To resolve the issue, increase the ULIMIT values of file handlers as described here:

  1. Log in as the root user.

  2. Open /etc/security/limits file.

  3. Edit the file and set the following values:

    • nofiles=8192

    • nofiles_hard=65536

  4. Reboot the machine to enable the changes.

Oracle HTTP Server Fails to Start due to Certificates Signed Using the MD5 Algorithm

Oracle HTTP Server fails to start if the Oracle HTTP Server wallet contains a certificate or certificate request that is signed with the Message Digest 5 (MD5) algorithm.

  • Solution: Replace the MD5 certificate with a Secure Hash Algorithm 2 (SHA-2) certificate.

  • Workaround: To enable MD5 supported certificate, set the ORACLE_SSL_ALLOW_MD5_CERT_SIGNATURES environment variable in the file to 1.

To set the environment variable in Oracle HTTP Server, see Environment Variable Configuration Properties.