diff --git a/blt/src/Blt/Plugin/Commands/HsCommands.php b/blt/src/Blt/Plugin/Commands/HsCommands.php
index 1ea3d7b2e..bc83770be 100644
--- a/blt/src/Blt/Plugin/Commands/HsCommands.php
+++ b/blt/src/Blt/Plugin/Commands/HsCommands.php
@@ -24,9 +24,10 @@ class HsCommands extends BltTasks {
    *
    * @aliases humsci:post-code-update
    */
-  public function postCodeDeployUpdate() {
+  public function postCodeDeployUpdate($target_env, $deployed_tag) {
     $sites = $this->getConfigValue('multisites');
-    $parallel_executions = 10;
+    $parallel_executions = (int) getenv('UPDATE_PARALLEL_PROCESSES') ?: 10;
+
     $site_chunks = array_chunk($sites, ceil(count($sites) / $parallel_executions));
     $commands = [];
     foreach ($site_chunks as $sites) {
@@ -50,11 +51,42 @@ public function postCodeDeployUpdate() {
         $failed[] = $site;
       }
     }
+    unlink(sys_get_temp_dir() . '/update-report.txt');
+
     $this->yell(sprintf('Updated %s sites successfully.', count($success)), 100);
+
     if ($failed) {
       $this->yell(sprintf("Update failed for the following sites:\n%s", implode("\n", $failed)), 100, 'red');
+
+      if (in_array($target_env, ['prod', 'test'])) {
+        $count = count($failed);
+        $this->sendSlackNotification("A new deployment has been made to *$target_env* using *$deployed_tag*.\n\n*$count* sites failed to update.");
+      }
+      throw new \Exception('Failed update');
     }
-    unlink(sys_get_temp_dir() . '/update-report.txt');
+
+    if (in_array($target_env, ['prod', 'test'])) {
+      $this->sendSlackNotification("A new deployment has been made to *$target_env* using *$deployed_tag*.");
+    }
+  }
+
+  /**
+   * Send out a slack notification.
+   *
+   * @param string $message
+   *   Slack message.
+   */
+  protected function sendSlackNotification(string $message) {
+    $client = new Client();
+    $client->post(getenv('SLACK_NOTIFICATION_URL'), [
+      'form_params' => [
+        'payload' => json_encode([
+          'username' => 'Acquia Cloud',
+          'text' => $message,
+          'icon_emoji' => 'information_source',
+        ]),
+      ],
+    ]);
   }
 
   /**
diff --git a/hooks/common/post-code-deploy/post-code-deploy.sh b/hooks/common/post-code-deploy/post-code-deploy.sh
index f0d34dcd7..28a359d20 100644
--- a/hooks/common/post-code-deploy/post-code-deploy.sh
+++ b/hooks/common/post-code-deploy/post-code-deploy.sh
@@ -24,6 +24,6 @@ repo_root="/var/www/html/$site.$target_env"
 export PATH=$repo_root/vendor/bin:$PATH
 cd $repo_root
 
-blt humsci:post-code-deploy
+blt humsci:post-code-deploy $target_env $deployed_tag
 
 set +v
diff --git a/hooks/common/post-code-update/post-code-update.sh b/hooks/common/post-code-update/post-code-update.sh
index f91897a9f..ae324c744 100644
--- a/hooks/common/post-code-update/post-code-update.sh
+++ b/hooks/common/post-code-update/post-code-update.sh
@@ -27,6 +27,6 @@ repo_root="/var/www/html/$site.$target_env"
 export PATH=$repo_root/vendor/bin:$PATH
 cd $repo_root
 
-blt humsci:post-code-deploy
+blt humsci:post-code-deploy $target_env $deployed_tag
 
 set +v
diff --git a/hooks/prod/post-code-deploy/slack.sh b/hooks/prod/post-code-deploy/slack.sh
deleted file mode 100644
index 813d162b7..000000000
--- a/hooks/prod/post-code-deploy/slack.sh
+++ /dev/null
@@ -1,24 +0,0 @@
-#!/bin/sh
-#
-# Cloud Hook: post-code-deploy
-#
-# The post-code-deploy hook is run whenever you use the Workflow page to
-# deploy new code to an environment, either via drag-drop or by selecting
-# an existing branch or tag from the Code drop-down list. See
-# ../README.md for details.
-#
-# Usage: post-code-deploy site target-env source-branch deployed-tag repo-url
-#                         repo-type
-
-site="$1"
-target_env="$2"
-source_branch="$3"
-deployed_tag="$4"
-repo_url="$5"
-repo_type="$6"
-
-# Load the Slack webhook URL (which is not stored in this repo).
-. $HOME/slack_settings
-
-# Post deployment notice to Slack
-curl -X POST --data-urlencode "payload={\"username\": \"Acquia Cloud\", \"text\": \"A new deployment has been made to *$target_env* using *$deployed_tag*.\", \"icon_emoji\": \":information_source:\"}" $SLACK_WEBHOOK_URL
diff --git a/hooks/test/post-code-update/.gitignore b/hooks/test/post-code-update/.gitignore
new file mode 100644
index 000000000..e69de29bb
diff --git a/hooks/test/post-code-update/slack.sh b/hooks/test/post-code-update/slack.sh
deleted file mode 100644
index f0ea6eebd..000000000
--- a/hooks/test/post-code-update/slack.sh
+++ /dev/null
@@ -1,24 +0,0 @@
-#!/bin/sh
-#
-# Cloud Hook: post-code-deploy
-#
-# The post-code-deploy hook is run whenever you use the Workflow page to
-# deploy new code to an environment, either via drag-drop or by selecting
-# an existing branch or tag from the Code drop-down list. See
-# ../README.md for details.
-#
-# Usage: post-code-deploy site target-env source-branch deployed-tag repo-url
-#                         repo-type
-
-site="$1"
-target_env="$2"
-source_branch="$3"
-deployed_tag="$4"
-repo_url="$5"
-repo_type="$6"
-
-# Load the Slack webhook URL (which is not stored in this repo).
-. $HOME/slack_settings
-
-# Post deployment notice to Slack
-curl -X POST --data-urlencode "payload={\"username\": \"Acquia Cloud\", \"text\": \"A new deployment has been made to *$target_env* using tag *$deployed_tag*.\", \"icon_emoji\": \":information_source:\"}" $SLACK_WEBHOOK_URL