diff --git a/irs-api/src/main/java/org/eclipse/tractusx/irs/ess/bpn/validation/BPNIncidentValidation.java b/irs-api/src/main/java/org/eclipse/tractusx/irs/ess/bpn/validation/BPNIncidentValidation.java
index 4a80aacb95..e0efe30149 100644
--- a/irs-api/src/main/java/org/eclipse/tractusx/irs/ess/bpn/validation/BPNIncidentValidation.java
+++ b/irs-api/src/main/java/org/eclipse/tractusx/irs/ess/bpn/validation/BPNIncidentValidation.java
@@ -83,7 +83,7 @@ public static SupplyChainImpacted jobContainsIncidentBPNSs(
             final PartSiteInformationAsPlanned partSiteInformationAsPlanned, final List<String> incidentBPNs)
             throws InvalidAspectTypeFormatException {
         if (partSiteInformationAsPlanned.sites().stream().anyMatch(site -> site.catenaXSiteId() == null)) {
-            throw new InvalidAspectTypeFormatException("Site does not contain catenaXSiteId.");
+            throw new InvalidAspectTypeFormatException("'PartSiteInformationAsPlanned' exists, but catenaXSiteId could not be found.");
         }
         final List<String> siteIds = partSiteInformationAsPlanned.getCatenaXSiteId();
         try {
diff --git a/irs-api/src/test/java/org/eclipse/tractusx/irs/ess/service/InvestigationJobProcessingEventListenerTest.java b/irs-api/src/test/java/org/eclipse/tractusx/irs/ess/service/InvestigationJobProcessingEventListenerTest.java
index 3022047479..19a69f428e 100644
--- a/irs-api/src/test/java/org/eclipse/tractusx/irs/ess/service/InvestigationJobProcessingEventListenerTest.java
+++ b/irs-api/src/test/java/org/eclipse/tractusx/irs/ess/service/InvestigationJobProcessingEventListenerTest.java
@@ -330,7 +330,7 @@ void shouldCreateTombstoneWhenSiteIdIsMissing() throws EdcClientException {
         final Optional<BpnInvestigationJob> job = bpnInvestigationJobCache.findByJobId(jobId);
         assertThat(job).isPresent();
         assertThat(job.get().getJobSnapshot().getTombstones()).hasSize(1);
-        assertThat(job.get().getJobSnapshot().getTombstones().get(0).getProcessingError().getErrorDetail()).isEqualTo("Site does not contain catenaXSiteId.");
+        assertThat(job.get().getJobSnapshot().getTombstones().get(0).getProcessingError().getErrorDetail()).isEqualTo("'PartSiteInformationAsPlanned' exists, but catenaXSiteId could not be found.");
     }
 
     private void createMockForJobIdAndShell(final UUID mockedJobId, final String mockedShell,
diff --git a/local/testing/api-tests/irs-api-tests.tavern.yaml b/local/testing/api-tests/irs-api-tests.tavern.yaml
index 632f4cfb2c..d8127916c8 100644
--- a/local/testing/api-tests/irs-api-tests.tavern.yaml
+++ b/local/testing/api-tests/irs-api-tests.tavern.yaml
@@ -493,7 +493,7 @@ stages:
         - function: local.testing.api-tests.tavern_helpers:supplyChainImpacted_is_Unknown
         - function: local.testing.api-tests.tavern_helpers:tombstone_for_EssValidation_are_correct
           extra_kwargs:
-            expectedTombstone: "Site does not contain catenaXSiteId."
+            expectedTombstone: "'PartSiteInformationAsPlanned' exists, but catenaXSiteId could not be found."
       headers:
         content-type: application/json