diff --git a/config/current.ver b/config/current.ver
index 4582474..930a24b 100644
--- a/config/current.ver
+++ b/config/current.ver
@@ -1 +1 @@
-1.2.25
\ No newline at end of file
+1.2.26
\ No newline at end of file
diff --git a/src/ApiKernel.php b/src/ApiKernel.php
index 86373b7..a46a8b7 100644
--- a/src/ApiKernel.php
+++ b/src/ApiKernel.php
@@ -1324,6 +1324,33 @@ class ApiKernel
         $contentId = (int)$this->val($this->in, ['content_id', 'content'], 0);
         if ($contentId <= 0) $this->fail('content_id required', null, 422);
 
+        $refsDebug = [];
+        $refs = $this->findTemplateReferences($customerId, $contentId, $refsDebug);
+        if (!empty($refsDebug)) {
+            $this->writeDebugLog('templates_references_debug', $refsDebug);
+        }
+        if (!empty($refs)) {
+            debug_log_write('templates_toggle', [
+                'time' => date(DATE_ATOM),
+                'action' => 'content_versions.deactivate.blocked',
+                'customer_id' => $customerId,
+                'content_id' => $contentId,
+                'references' => $refs,
+                'input' => $this->in,
+            ], [
+                'append' => true,
+                'json' => true,
+                'newline' => true,
+            ]);
+            $this->respond([
+                'ok' => false,
+                'error' => 'Template wird in anderen Templates verwendet',
+                'content_id' => $contentId,
+                'count' => count($refs),
+                'references' => $refs,
+            ], 409);
+        }
+
         $ok = $this->deactivateContentVersion($customerId, $contentId);
         debug_log_write('templates_toggle', [
             'time' => date(DATE_ATOM),