diff --git a/docs/en/00_Getting_Started/01_Installation/05_Common_Problems.md b/docs/en/00_Getting_Started/01_Installation/05_Common_Problems.md
index ff9a1cd6a..5fc5f5110 100644
--- a/docs/en/00_Getting_Started/01_Installation/05_Common_Problems.md
+++ b/docs/en/00_Getting_Started/01_Installation/05_Common_Problems.md
@@ -12,14 +12,8 @@ detailed error messages for security reasons. You'll typically need to get your
 information.
 
 If you can log-in to the CMS as an administrator, append `?isDev=1` to any URL to temporarily set your browsing session into
-"dev mode". If you can't log-in in the first place because of the error, add this directive to your `mysite/_config/config.yml`
-(don't forget to remove it afterwards!):
-
-```yml
-	Director:
-	  # temporary debugging statement
-	  environment_type: 'dev'
-```
+"dev mode". If you can't log-in in the first place because of the error, please
+configure an `SS_ENVIRONMENT_TYPE` through [environment-management] (don't forget to remove it afterwards!).
 
 <div class="warning" markdown='1'>
 On "live" environments, the `?isDev=1` solution is preferred, as it means that your other visitors don't see ugly
diff --git a/docs/en/02_Developer_Guides/07_Debugging/00_Environment_Types.md b/docs/en/02_Developer_Guides/07_Debugging/00_Environment_Types.md
index d8a537a04..132e36963 100644
--- a/docs/en/02_Developer_Guides/07_Debugging/00_Environment_Types.md
+++ b/docs/en/02_Developer_Guides/07_Debugging/00_Environment_Types.md
@@ -4,22 +4,8 @@ summary: Configure your SilverStripe environment to define how your web applicat
 # Environment Types
 
 SilverStripe knows three different environment types (or "modes"). Each of the modes gives you different tools
-and behaviors. The environment is managed either through a [YML configuration file](../configuration) or in a 
+and behaviors. The environment is managed either through an 
 [environment configuration file](../../getting_started/environment_management).
-
-The definition of setting an environment type in a `mysite/_config/app.yml` looks like
-
-
-```yml
-
-    SilverStripe\Control\Director:
-      environment_type: 'dev'
-```
-
-The definition of setting an environment type in a `.env` file looks like
-```
-    SS_ENVIRONMENT_TYPE="dev"
-```
 The three environment types you can set are `dev`, `test` and `live`.
 
 ### Dev
diff --git a/docs/en/04_Changelogs/4.0.0.md b/docs/en/04_Changelogs/4.0.0.md
index dd7a8af17..c7d907f8e 100644
--- a/docs/en/04_Changelogs/4.0.0.md
+++ b/docs/en/04_Changelogs/4.0.0.md
@@ -1797,9 +1797,11 @@ that it belongs to, e.g. `themes/mytheme/templates/MyVendor/Foobar/Model/MyModel
   All static methods have been removed, and the `inst_` prefix removed from all instance members.
   Please see the upgrading section on Session object for more details.
 * `Director.rules` config no longer support `redirect:<url>` directly via config.
-* `Director::get_environment_type()` and `Director::set_environment_type()` are removed.
+* `Director::get_environment_type()` and `Director::set_environment_type()` are removed. 
   Get the `Kernel` instance via injector and query `getEnvironment()` instead.
   E.g. `$type = Injector::inst()->get(Kernel::class)->getEnvironment();`.
+* The environment can no longer be configured via YAML (`Director.environment_type`).
+  Use a [.env file](/getting_started/environment_management) to manage environment settings.
 * Many global methods have been refactored into `Environment` or `Convert` class.
   * `increase_xdebug_nesting_level_to` removed (functionality has been inlined into `AppKernel`)
   * `set_increase_time_limit_max` moved to `Environment::setTimeLimitMax()`
diff --git a/src/Control/Director.php b/src/Control/Director.php
index 90d73807b..109135cf1 100644
--- a/src/Control/Director.php
+++ b/src/Control/Director.php
@@ -22,12 +22,8 @@ use SilverStripe\View\TemplateGlobalProvider;
  * The most important part of director is {@link Director::handleRequest()}, which is passed an HTTPRequest and will
  * execute the appropriate controller.
  *
- * Director also has a number of static methods that provide information about the environment, such as
- * {@link Director::$environment_type}.
- *
  * @see Director::handleRequest()
  * @see Director::$rules
- * @see Director::$environment_type
  * @skipUpgrade
  */
 class Director implements TemplateGlobalProvider
@@ -98,14 +94,6 @@ class Director implements TemplateGlobalProvider
      */
     private static $default_base_url = '`SS_BASE_URL`';
 
-    /**
-     * Assigned environment type
-     *
-     * @internal
-     * @var string
-     */
-    protected static $environment_type;
-
     public function __construct()
     {
     }