diff --git a/FitConnect/Services/Models/v1/Api/Problems.cs b/FitConnect/Services/Models/v1/Api/Problems.cs
index 13c5e5fccb37126c7f656b106dd6164f83e70587..2925db9d59edb0d9d9f5d36082021126a25a4fe2 100644
--- a/FitConnect/Services/Models/v1/Api/Problems.cs
+++ b/FitConnect/Services/Models/v1/Api/Problems.cs
@@ -4,11 +4,11 @@ using Newtonsoft.Json;
 namespace FitConnect.Models.v1.Api;
 
 public class Problems {
-
     public enum ProblemTypeEnum {
         AttachmentMismatch,
         MissingAttachments,
         EncryptionIssue,
+        HashMismatch,
         IncorrectAuthenticationTag,
         InvalidEventLog,
         MissingAuthenticationTag,
@@ -26,18 +26,20 @@ public class Problems {
     internal Problems() {
     }
 
-    public Problems(ProblemTypeEnum problemType, string title, string detail, ProblemInstanceEnum problemInstance) {
-        this.type = problemType switch {
-            ProblemTypeEnum.MissingAttachments => "https://schema.fitko.de/fit-connect/events/problems/missing-attachment",
-            ProblemTypeEnum.AttachmentMismatch => "https://schema.fitko.de/fit-connect/problems/attachments-mismatch",
-            ProblemTypeEnum.EncryptionIssue => "https://schema.fitko.de/fit-connect/problems/encryption-issue",
-            ProblemTypeEnum.IncorrectAuthenticationTag => "https://schema.fitko.de/fit-connect/problems/incorrect-authentication-tag",
-            ProblemTypeEnum.InvalidEventLog => "https://schema.fitko.de/fit-connect/problems/invalid-event-log",
-            ProblemTypeEnum.MissingAuthenticationTag => "https://schema.fitko.de/fit-connect/problems/missing-authentication-tag",
-            ProblemTypeEnum.MissingSchema => "https://schema.fitko.de/fit-connect/problems/missing-schema",
-            ProblemTypeEnum.SchemaViolation => "https://schema.fitko.de/fit-connect/problems/schema-violation",
-            ProblemTypeEnum.SyntaxViolation => "https://schema.fitko.de/fit-connect/problems/syntax-violation",
-            ProblemTypeEnum.UnsupportedSchema => "https://schema.fitko.de/fit-connect/problems/unsupported-schema",
+    public Problems(ProblemTypeEnum problemType, string title, string detail,
+        ProblemInstanceEnum problemInstance) {
+        this.type = "https://schema.fitko.de/fit-connect/events/problems/" + problemType switch {
+            ProblemTypeEnum.MissingAttachments => "missing-attachment",
+            ProblemTypeEnum.AttachmentMismatch => "attachments-mismatch",
+            ProblemTypeEnum.EncryptionIssue => "encryption-issue",
+            ProblemTypeEnum.HashMismatch => "hash-mismatch",
+            ProblemTypeEnum.IncorrectAuthenticationTag => "incorrect-authentication-tag",
+            ProblemTypeEnum.InvalidEventLog => "invalid-event-log",
+            ProblemTypeEnum.MissingAuthenticationTag => "missing-authentication-tag",
+            ProblemTypeEnum.MissingSchema => "missing-schema",
+            ProblemTypeEnum.SchemaViolation => "schema-violation",
+            ProblemTypeEnum.SyntaxViolation => "syntax-violation",
+            ProblemTypeEnum.UnsupportedSchema => "unsupported-schema",
             _ => throw new ArgumentOutOfRangeException(nameof(problemType), problemType, null)
         };
 
@@ -51,62 +53,66 @@ public class Problems {
         };
     }
 
-    public static readonly Problems AttachmentsMismatch = 
+    public static readonly Problems AttachmentsMismatch =
         new Problems(
-            ProblemTypeEnum.AttachmentMismatch, 
+            ProblemTypeEnum.AttachmentMismatch,
             "Fehlerhafte Anlagen-Liste",
             "Die Liste der Anlagen in Submission und Event-Log stimmt nicht überein.",
             ProblemInstanceEnum.Submission);
 
-    public static readonly Problems EncryptionIssue = 
+    public static readonly Problems EncryptionIssue =
         new Problems(
             ProblemTypeEnum.EncryptionIssue,
             "Entschlüsselungs-Fehler",
             "Der Schlüssel {kid} ist nicht der zu diesem Zweck vorgesehene Schlüssel.",
             ProblemInstanceEnum.Metadata
         );
-        
-    public static readonly Problems IncorrectAuthenticationTag = 
-        new Problems( 
+
+    public static readonly Problems IncorrectAuthenticationTag =
+        new Problems(
             ProblemTypeEnum.IncorrectAuthenticationTag,
             "Authentication-Tag ungültig",
             "Das Authentication-Tag des Metadatensatzes ist ungültig.",
             ProblemInstanceEnum.Metadata
         );
-    public static readonly Problems InvalidEventLog = 
-        new Problems (
+
+    public static readonly Problems InvalidEventLog =
+        new Problems(
             ProblemTypeEnum.InvalidEventLog,
             "Inkonsistentes Event-Log",
             "Das Event-Log ist inkonsistent, da es nicht genau ein Event 'submit-submission' enthält.",
             ProblemInstanceEnum.Submission
         );
-       
-    public static readonly Problems MissingAuthenticationTag = 
-        new Problems (
+
+    public static readonly Problems MissingAuthenticationTag =
+        new Problems(
             ProblemTypeEnum.MissingAuthenticationTag,
             "Fehlende Authentication-Tags",
             "Das Event 'submit-submission' enthält keine Authentication-Tags.",
             ProblemInstanceEnum.Submission
         );
-       
+
     public static readonly Problems MissingSchema = new Problems(
         ProblemTypeEnum.MissingSchema,
         "Schema-Referenz fehlt",
         "Die Schema-Referenz fehlt im Metadatensatz.",
         ProblemInstanceEnum.Metadata
     );
-    public static readonly Problems SchemaViolation = new Problems (
+
+    public static readonly Problems SchemaViolation = new Problems(
         ProblemTypeEnum.SchemaViolation,
         "Schema-Fehler",
         "Der Metadatensatz ist nicht schema-valide.",
         ProblemInstanceEnum.Metadata
     );
+
     public static readonly Problems SyntaxViolation = new Problems(
         ProblemTypeEnum.SyntaxViolation,
         "Syntax-Fehler",
         "Der Metadatensatz ist kein valides JSON.",
         ProblemInstanceEnum.Metadata
     );
+
     public static readonly Problems UnsupportedSchema = new Problems(
         ProblemTypeEnum.UnsupportedSchema,
         "Metadatenschema nicht unterstützt",
@@ -115,8 +121,6 @@ public class Problems {
     );
 
 
-       
-
     [JsonProperty("instance", NullValueHandling = NullValueHandling.Ignore)]
     public string instance { get; set; }
 
@@ -134,5 +138,4 @@ public class Problems {
 
     // [JsonProperty("items", NullValueHandling = NullValueHandling.Ignore)]
     // public Items? items { get; set; }
-        
 }