CiviCRM Community Forums (archive)

FWIW, the warning is only relevant to some extensions -- it depends on how the extension is distributed. (Extensions distributed via github.com are generally affected because github always sends an HTTP redirect; other distributors often aren't affected.) When installing the extension, you should see some advanced details which include the download URL.

Generally, there are two possibilities:

• Downloading files with HTTP redirection does not work in your PHP runtime. It can be fixed by changing the system config -- or by spending a few hours patching/testing CRM_Utils_HttpClient to use a work-around.
• The system does actually support HTTP redirects but erroneously displays the message. In this case, one needs to change the conditional/test that it looks for ( https://github.com/civicrm/civicrm-core/blob/4.5/CRM/Utils/HttpClient.php#L216 ).

A few debugging techniques have come up in previous conversations:

• Hack CRM_Utils_HttpClient::isRedirectionSupported() to force it to always return true; see if the extension downloads work
• Print out & report the details used by isRedirectionSupported(). This can be done by temporarily creating/viewing a new .php file in the webroot like:

<?php
echo "<pre>";
var_dump(array(
  'values' => array(
    "ini_get('open_basedir')" => ini_get('open_basedir'),
    "ini_get('safe_mode')" => ini_get('safe_mode'),
  ),
  'conditions' => array(
    "ini_get('open_basedir') == ''" =>  ini_get('open_basedir') == '',
    "ini_get('safe_mode') == 'Off'" => ini_get('safe_mode') == 'Off',
    "ini_get('safe_mode') == ''" => ini_get('safe_mode') == '',
    "ini_get('safe_mode') === FALSE" => ini_get('safe_mode') === FALSE,
    "(ini_get('safe_mode') == 'Off' || ini_get('safe_mode') == '' || ini_get('safe_mode') === FALSE)"
      => (ini_get('safe_mode') == 'Off' || ini_get('safe_mode') == '' || ini_get('safe_mode') === FALSE)
   ),
));

More discussion on the topic at https://issues.civicrm.org/jira/browse/CRM-14126 .