diff --git a/EnvelopeGenerator.Application/Envelopes/Queries/ReadSingleEnvelopeQuery.cs b/EnvelopeGenerator.Application/Envelopes/Queries/ReadSingleEnvelopeQuery.cs
index feae8002..7c7c735f 100644
--- a/EnvelopeGenerator.Application/Envelopes/Queries/ReadSingleEnvelopeQuery.cs
+++ b/EnvelopeGenerator.Application/Envelopes/Queries/ReadSingleEnvelopeQuery.cs
@@ -5,13 +5,14 @@ using AutoMapper;
 using DigitalData.Core.Abstraction.Application.Repository;
 using EnvelopeGenerator.Domain.Entities;
 using Microsoft.EntityFrameworkCore;
+using DigitalData.Core.Exceptions;
 
 namespace EnvelopeGenerator.Application.Envelopes.Queries;
 
 /// <summary>
 /// Repräsentiert eine Abfrage für einen einzelnen Umschlag.
 /// </summary>
-public record ReadSingleEnvelopeQuery : EnvelopeQueryBase, IRequest<EnvelopeDto?>
+public record ReadSingleEnvelopeQuery : EnvelopeQueryBase, IRequest<EnvelopeDto>
 {
     /// <summary>
     /// Optionaler Benutzerfilter; wenn gesetzt, werden nur Umschläge des Benutzers geladen.
@@ -27,7 +28,7 @@ public record ReadSingleEnvelopeQuery : EnvelopeQueryBase, IRequest<EnvelopeDto?
 /// <summary>
 /// Verarbeitet <see cref="ReadSingleEnvelopeQuery"/> und liefert ein einzelnes <see cref="EnvelopeDto"/>-Ergebnis.
 /// </summary>
-public class ReadSingleEnvelopeQueryHandler : IRequestHandler<ReadSingleEnvelopeQuery, EnvelopeDto?>
+public class ReadSingleEnvelopeQueryHandler : IRequestHandler<ReadSingleEnvelopeQuery, EnvelopeDto>
 {
     private readonly IRepository<Envelope> _repository;
     private readonly IMapper _mapper;
@@ -49,7 +50,7 @@ public class ReadSingleEnvelopeQueryHandler : IRequestHandler<ReadSingleEnvelope
     /// <param name="request"></param>
     /// <param name="cancel"></param>
     /// <returns></returns>
-    public async Task<EnvelopeDto?> Handle(ReadSingleEnvelopeQuery request, CancellationToken cancel)
+    public async Task<EnvelopeDto> Handle(ReadSingleEnvelopeQuery request, CancellationToken cancel)
     {
         var query = _repository.Query;
 
@@ -61,11 +62,17 @@ public class ReadSingleEnvelopeQueryHandler : IRequestHandler<ReadSingleEnvelope
 
         if (request.Uuid is string uuid)
             query = query.Where(e => e.Uuid == uuid);
-
-        var envelope = await query
+        
+        var envelopes = await query
             .Include(e => e.Documents)
-            .FirstOrDefaultAsync(cancel);
+            .Take(2)
+            .ToListAsync(cancel);
 
-        return envelope is null ? null : _mapper.Map<EnvelopeDto>(envelope);
+        if (envelopes.Count > 1)
+            throw new BadRequestException($"Multiple envelopes found for the given criteria: Id={request.Id}, Uuid={request.Uuid}, UserId={request.UserId}");
+
+        return envelopes.SingleOrDefault() is Envelope envelope
+            ? _mapper.Map<EnvelopeDto>(envelope)
+            : throw new NotFoundException($"Envelope with Id={request.Id}, Uuid={request.Uuid} not found");
     }
-}
+}
\ No newline at end of file