diff --git a/src/validation/getFlowValidation.ts b/src/validation/getFlowValidation.ts
index 90fd67a..67fc36d 100644
--- a/src/validation/getFlowValidation.ts
+++ b/src/validation/getFlowValidation.ts
@@ -12,6 +12,34 @@ export const getFlowValidation = (
 ): ValidationResult => {
 
 
+    if (!flow?.startingNodeId) {
+        return {
+            isValid: false,
+            returnType: "void",
+            diagnostics: [{
+                nodeId: null,
+                parameterIndex: null,
+                code: 0,
+                message: "You need to provide a starting node to be able to execute this flow.",
+                severity: "error",
+            }]
+        }
+    }
+
+    if (!flow.nodes?.nodes?.find(n => n?.id == flow.startingNodeId)) {
+        return {
+            isValid: false,
+            returnType: "void",
+            diagnostics: [{
+                nodeId: null,
+                parameterIndex: null,
+                code: 0,
+                message: "The starting node is not linked within the flow. Please make sure the starting node is connected to the rest of the flow.",
+                severity: "error",
+            }]
+        }
+    }
+
     const sourceCode = generateFlowSourceCode(flow, functions, dataTypes);
 
     // 3. Virtual TypeScript Compilation
diff --git a/test/flowValidation.test.ts b/test/flowValidation.test.ts
index 772c7ea..f0394f7 100644
--- a/test/flowValidation.test.ts
+++ b/test/flowValidation.test.ts
@@ -8,6 +8,7 @@ describe('getFlowValidation - Integrationstest', () => {
     it('1', () => {
 
         const flow: Flow = {
+            startingNodeId: "gid://sagittarius/NodeFunction/1",
             nodes: {
                 nodes: [
                     {
@@ -51,7 +52,7 @@ describe('getFlowValidation - Integrationstest', () => {
                                         __typename: "ReferenceValue",
                                         nodeFunctionId: "gid://sagittarius/NodeFunction/2",
                                         parameterIndex: 1,
-                                        inputIndex: 0, //TODO: Das wird gerade einfach nicht berücksichtigt
+                                        inputIndex: 0,
                                         referencePath: [{path: "test"}]
                                     }
                                 },
@@ -149,6 +150,7 @@ describe('getFlowValidation - Integrationstest', () => {
     it('4', () => {
 
         const flow: Flow = {
+            startingNodeId: "gid://sagittarius/NodeFunction/1",
             nodes: {
                 nodes: [
                     {
@@ -198,6 +200,7 @@ describe('getFlowValidation - Integrationstest', () => {
     it('5', () => {
 
         const flow: Flow = {
+            startingNodeId: "gid://sagittarius/NodeFunction/2",
             nodes: {
                 nodes: [
                     {