Merge pull request #1119 from ExpressionEngine/fix/live-preview-troubleshoot

Adding docs on troubleshooting Live Preview http auth issues

Author: TomJaeger

docs/control-panel/create.md

@@ -192,10 +192,12 @@ Saves the entry and returns the [Entry Manager](control-panel/entry-manager.md)
 
 ### Preview
 
-A live preview of the entry is available if the `channel_prefs_preview_url` is set **or** the [Pages Module](add-ons/pages.md) is installed and a Page URI and template have been set.
+A live preview of the entry is available if the relevant channel's [Preview URL](control-panel/channels.md#settings-tab) is set **or** the [Pages Module](add-ons/pages.md) or [Structure](add-ons/structure/overview.md) is installed and configured with a URI and template.
 
 If neither is set, the preview button will have an exclamation mark (!) and will link to channel preferences page where Preview URL can be set.
 
-The preview will open a split screen that allows a live preview of edits. The template used to display the preview is based on the Page fields if set and the channel preview URL otherwise.
+The preview will open a split screen that allows a live preview of edits. The template used to display the preview is based on configured Pages/Structure fields if set and the channel preview URL otherwise.
 
 When the preview is triggered, it is being displayed side-by-side with edit screen. The size of preview container can be adjusted with mouse dragging its border. The preview is dynamically being updated as you change the fields.
+
+Live Preview does require the [HTTP Authorization Header be enabled](troubleshooting/error-messages.md#http-authorization-header-missing).

docs/installation/requirements.md

@@ -117,6 +117,12 @@ If you are hosted on an Apache server, the `AcceptPathInfo` option needs to be e
 - Ask your web host or server admin to enable the option
 - Set your site's URLs to use [query strings](general/url-structure.md#query-strings)
 
+If on an Apache server and [Live Preview](control-panel/create.md#preview) shows an error message 'HTTP Authorization Header Missing', you will need to add this line of code to your [.htaccess file](installation/best-practices.md#1-create-an-htaccess-file)
+
+```php
+SetEnvIf Authorization "(.*)" HTTP_AUTHORIZATION=$1
+```
+
 ### URL Segment Support
 
 If the [Server Compatibility Wizard](#server-compatibility-wizard) lists URL Segment Support as _Unsupported_, you will need to set your site's URLs to use [query strings](general/url-structure.md#query-strings).

docs/troubleshooting/error-messages.md

@@ -45,6 +45,17 @@ This error---and similar warnings such as **"Warning: imagettftext(): Could not
 
 If that is not an option, **Use TrueType Font for Captcha?** should be set to _No_ under `Settings --> CAPTCHA` or CAPTCHAs should be disabled altogether.
 
+## HTTP Authorization Header Missing
+
+ExpressionEngine returns the following error message when attempting to use [Live Preview](control-panel/create.md#preview): **"HTTP Authorization Header Missing"**
+
+### Troubleshooting
+
+The Authorization header is stripped by some Apache servers, causing an error rendering the Live Preview. This behavior may be overridden in your [.htaccess file](installation/best-practices.md#1-create-an-htaccess-file) by adding the following line:
+
+```php
+SetEnvIf Authorization "(.*)" HTTP_AUTHORIZATION=$1
+```
 ## Warning: Cannot modify header information
 
 ExpressionEngine returns the following warning: **"Cannot modify header information."**