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Troubleshooting Dispatcher Problems

Dispatcher versions are independent of AEM, however the Dispatcher documentation is embedded in the AEM documentation. Always use the Dispatcher documentation that is embedded in the documentation for the latest version of AEM.
You may have been redirected to this page if you followed a link to the Dispatcher documentation that is embedded in the documentation for a previous version of AEM.

Check the Basic Configuration

As always the first steps are to check the basics:
  • Check all log files for your web server and dispatcher. If necessary increase the
    loglevel
    used for the dispatcher logging .
    • Do you have multiple Dispatchers?
      • Have you determined which Dispatcher is handling the website / page you are investigating?
    • Have you implemented filters?
      • Are these impacting the matter you are investigating?

IIS Diagnostic Tools

IIS provides various trace tools, dependent on the actual version:
  • IIS 6 - IIS diagnostic tools can be downloaded and configured
  • IIS 7 - tracing is fully integrated
These can help you monitor activity.

IIS and 404 Not Found

When using IIS you might experience
404 Not Found
being returned in various scenarios. If so, see the following Knowledge Base articles.
You should also check that the dispatcher cache root and the IIS document root are set to the same directory.

Problems Deleting Workflow Models

Symptoms
Problems trying to delete workflow models when accessing an AEM author instance through the Dispatcher.
Steps to reproduce:
  1. Log in to your author instance (confirm that requests are being routed through the dispatcher).
  2. Create a new workflow; for example, with the Title set to workflowToDelete.
  3. Confirm that the workflow was successfully created.
  4. Select and right click on the workflow, then click
    Delete
    .
  5. Click
    Yes
    to confirm.
  6. An error message box will appear showing: "
    ERROR 'Could not delete workflow model!!
    ".
Resolution
Add the following headers to the
/clientheaders
section of your
dispatcher.any
file:
  • x-http-method-override
  • x-requested-with
{ { /clientheaders { ... "x-http-method-override" "x-requested-with" }

Interference with mod_dir (Apache)

This describes how the dispatcher interacts with
mod_dir
inside the Apache webserver, as this can lead to various, potentially unexpected effects:

Apache 1.3

In Apache 1.3
mod_dir
handles every request where the URL maps to a directory in the file system.
It will either:
  • redirect the request to an existing
    index.html
    file
  • generate a directory listing
When the dispatcher is enabled, it processes such requests by registering itself as a handler for the content type
httpd/unix-directory
.

Apache 2.x

In Apache 2.x things are different. A module can handle different stages of the request, such as URL fixup.
mod_dir
handles this stage by redirecting a request (when the URL maps to a directory) to the URL with a
/
appended.
Dispatcher does not intercept the
mod_dir
fixup, but completely handles the request to the redirected URL (i.e. with
/
appended). This might pose a problem if the remote server (e.g. AEM) handles requests to
/a_path
differently to requests to
/a_path/
(when
/a_path
maps to an existing directory).
If this happens you must either:
  • disable
    mod_dir
    for the
    Directory
    or
    Location
    subtree handled by the dispatcher
  • use
    DirectorySlash Off
    to configure
    mod_dir
    not to append
    /