diff --git a/js/customElements/blogFooter.js b/js/customElements/blogFooter.js
index 999f63584bfc447b727b0d0e5fcffac6d4e2d726..7d11c41193a9bf03319ac8251120a0ed7a80afdf 100644
--- a/js/customElements/blogFooter.js
+++ b/js/customElements/blogFooter.js
@@ -15,6 +15,7 @@ class blogFooter extends HTMLElement {
         var requestOptions = {
         method: 'POST',
         body: graphql,
+        headers: { 'Content-Type': 'application/json' }
         };
         let posts = (await (await fetch("/API/graphql.php", requestOptions)).json()).data.blogPosts;
         posts.forEach((element) => {
diff --git a/js/customElements/blogIndex.js b/js/customElements/blogIndex.js
index a1a95cfaf935de618ba4ac2bce7a663766fae75d..342f08cffe85a20b65873d113602dc192cab2344 100644
--- a/js/customElements/blogIndex.js
+++ b/js/customElements/blogIndex.js
@@ -15,6 +15,7 @@ class BlogIndex extends HTMLElement {
         var requestOptions = {
         method: 'POST',
         body: graphql,
+        headers: { 'Content-Type': 'application/json' }
         };
         let posts = (await (await fetch("/API/graphql.php", requestOptions)).json()).data.blogPosts;
         posts.forEach((element) => {
diff --git a/js/customElements/commentsDisplay.js b/js/customElements/commentsDisplay.js
index e301dd1799f9d3df274195b4cc1aefcee1dcc8de..3243502483b9d63517e6a02d0c51a51fd829a459 100644
--- a/js/customElements/commentsDisplay.js
+++ b/js/customElements/commentsDisplay.js
@@ -14,6 +14,7 @@ class commentsDisplay extends HTMLElement {
         var requestOptions = {
         method: 'POST',
         body: graphql,
+        headers: { 'Content-Type': 'application/json' }
         };
         let comments = (await (await fetch("/API/graphql.php", requestOptions)).json()).data.comments;
         this.innerHTML = "";
diff --git a/js/customElements/contactMailButton.js b/js/customElements/contactMailButton.js
index 5d1aa176d7e9ca91b63289db5bd71bafacda980f..b1f138f321c3e6466577fe5da3f0417f803a62ca 100644
--- a/js/customElements/contactMailButton.js
+++ b/js/customElements/contactMailButton.js
@@ -12,6 +12,7 @@ class contactMailButton extends HTMLElement {
           var requestOptions = {
             method: 'POST',
             body: graphql,
+            headers: { 'Content-Type': 'application/json' }
           };
 
         let sitekey = (await (await fetch("/API/graphql.php", requestOptions)).json()).data.sitekey;
diff --git a/js/customElements/ebkBanner.js b/js/customElements/ebkBanner.js
index 2818b20302564e4117291ee0742b8657d70b04bd..2171dd335306ab14503f16f4594765bfb753c7d3 100644
--- a/js/customElements/ebkBanner.js
+++ b/js/customElements/ebkBanner.js
@@ -11,6 +11,7 @@ class ebkBanner extends HTMLElement {
         var requestOptions = {
             method: 'POST',
             body: graphql,
+            headers: { 'Content-Type': 'application/json' }
         };
         let elementCount = (await (await fetch("/API/graphql.php", requestOptions)).json()).data.ebayKleinanzeigen.count;
         if(elementCount > 0) {
diff --git a/js/customElements/newComment.js b/js/customElements/newComment.js
index 54f0e4bd0b76e41823d987df4d814c3de0cd7e86..b7c372ff731be1d37f9f0552268b6a5645df8704 100644
--- a/js/customElements/newComment.js
+++ b/js/customElements/newComment.js
@@ -15,6 +15,7 @@ class newComment extends HTMLElement {
         var requestOptions = {
             method: 'POST',
             body: graphql,
+            headers: { 'Content-Type': 'application/json' }
         };
 
         let sitekey = (await (await fetch("/API/graphql.php", requestOptions)).json()).data.sitekey;
@@ -117,6 +118,7 @@ class newComment extends HTMLElement {
                 var requestOptions = {
                     method: 'POST',
                     body: graphql,
+                    headers: { 'Content-Type': 'application/json' }
                 };
                 let data = (await (await fetch("/API/graphql.php", requestOptions)).json()).data;
                 if (data.newComment == "OK") {
diff --git a/js/customElements/sellingTable.js b/js/customElements/sellingTable.js
index bfd448292a62f95096b9b2717448ff864c35c28b..c9c11a6ecc2a78bf6ff1ce08b5ff0203b0957921 100644
--- a/js/customElements/sellingTable.js
+++ b/js/customElements/sellingTable.js
@@ -59,6 +59,7 @@ class sellingTable extends HTMLElement {
         var requestOptions = {
             method: 'POST',
             body: graphql,
+            headers: { 'Content-Type': 'application/json' }
         };
         let elements = (await (await fetch("/API/graphql.php", requestOptions)).json()).data.ebayKleinanzeigen.elements;
         elements.forEach(ad => {
diff --git a/js/customElements/skills.js b/js/customElements/skills.js
index c37631b016f7d8cb658b51f096baf9776440d327..383952a8fb89802cc7a058f21d66f78cda82a7c2 100644
--- a/js/customElements/skills.js
+++ b/js/customElements/skills.js
@@ -11,6 +11,7 @@ class Skill extends HTMLElement {
           var requestOptions = {
             method: 'POST',
             body: graphql,
+            headers: { 'Content-Type': 'application/json' }
           };
 
         let skills = (await (await fetch("/API/graphql.php", requestOptions)).json()).data.skills;
diff --git a/js/viewPost.js b/js/viewPost.js
index be5bda802fdf743bff1506722f59755d5dcbec07..15e8261046a408df987db402464a97ece15445ae 100644
--- a/js/viewPost.js
+++ b/js/viewPost.js
@@ -29,6 +29,7 @@ async function loadPost() {
         var requestOptions = {
         method: 'POST',
         body: graphql,
+        headers: { 'Content-Type': 'application/json' }
         };
         let post = (await (await fetch("/API/graphql.php", requestOptions)).json()).data.blogPost;
         content.innerHTML = post["content"];
diff --git a/public/API/graphql.php b/public/API/graphql.php
index 0e8190a8ebf72d3986a18f1103540b8c46c461f4..b778f21a64d014ea29aaeb3a9e3897ff2842c477 100644
--- a/public/API/graphql.php
+++ b/public/API/graphql.php
@@ -1,5 +1,5 @@
 <?php
-use GraphQL\GraphQL;
+use GraphQL\Server\StandardServer;
 use GraphQL\Type\Schema;
 
 require 'vendor/autoload.php';
@@ -8,7 +8,8 @@ require "./lib/mysql.php";
 require "./queries/queries.php";
 
 $schema = new Schema([
-    'query' => $queryType
+    'query' => $queryType,
+    'mutation' => $mutationType,
 ]);
 
 try {
diff --git a/public/impressum.html b/public/impressum.html
index 62e7384222cf0dc431b1d07cefb48c381c2cf21e..c8246cdc745483b31ffb3bf61f79473f37807d92 100644
--- a/public/impressum.html
+++ b/public/impressum.html
@@ -59,6 +59,7 @@
                 var requestOptions = {
                 method: 'POST',
                 body: graphql,
+                headers: { 'Content-Type': 'application/json' }
                 };
                 let mailAddress = (await (await fetch("/API/graphql.php", requestOptions)).json()).data.mailAddress;