diff --git a/hapi-fhir-jpaserver-test-r4/src/test/java/ca/uhn/fhir/jpa/dao/r4/FhirResourceDaoR4ValidateTest.java b/hapi-fhir-jpaserver-test-r4/src/test/java/ca/uhn/fhir/jpa/dao/r4/FhirResourceDaoR4ValidateTest.java
index 3de4d680d9d..65eb5737e2b 100644
--- a/hapi-fhir-jpaserver-test-r4/src/test/java/ca/uhn/fhir/jpa/dao/r4/FhirResourceDaoR4ValidateTest.java
+++ b/hapi-fhir-jpaserver-test-r4/src/test/java/ca/uhn/fhir/jpa/dao/r4/FhirResourceDaoR4ValidateTest.java
@@ -228,7 +228,7 @@ public class FhirResourceDaoR4ValidateTest extends BaseJpaR4Test {
 		encoded = encode(oo);
 		ourLog.info(encoded);
 		assertThat(oo.getIssue()).hasSize(1);
-		assertEquals("CodeSystem is unknown and can't be validated: http://cs for 'http://cs#code1' (error because this is a required binding)", oo.getIssueFirstRep().getDiagnostics());
+		assertEquals("CodeSystem is unknown and can't be validated: http://cs for 'http://cs#code1'", oo.getIssueFirstRep().getDiagnostics());
 		assertEquals(OperationOutcome.IssueSeverity.WARNING, oo.getIssueFirstRep().getSeverity());
 
 		// Invalid code
@@ -334,7 +334,7 @@ public class FhirResourceDaoR4ValidateTest extends BaseJpaR4Test {
 		encoded = encode(oo);
 		ourLog.info(encoded);
 		assertThat(oo.getIssue()).hasSize(1);
-		assertEquals("CodeSystem is unknown and can't be validated: http://cs for 'http://cs#code1' (error because this is a required binding)", oo.getIssueFirstRep().getDiagnostics());
+		assertEquals("CodeSystem is unknown and can't be validated: http://cs for 'http://cs#code1'", oo.getIssueFirstRep().getDiagnostics());
 		assertEquals(OperationOutcome.IssueSeverity.WARNING, oo.getIssueFirstRep().getSeverity());
 
 		// Invalid code
@@ -343,7 +343,7 @@ public class FhirResourceDaoR4ValidateTest extends BaseJpaR4Test {
 		encoded = encode(oo);
 		ourLog.info(encoded);
 		assertThat(oo.getIssue()).hasSize(1);
-		assertEquals("CodeSystem is unknown and can't be validated: http://cs for 'http://cs#code99' (error because this is a required binding)", oo.getIssue().get(0).getDiagnostics());
+		assertEquals("CodeSystem is unknown and can't be validated: http://cs for 'http://cs#code99'", oo.getIssue().get(0).getDiagnostics());
 		assertEquals(OperationOutcome.IssueSeverity.WARNING, oo.getIssue().get(0).getSeverity());
 	}
 
diff --git a/hapi-fhir-validation/src/main/java/org/hl7/fhir/common/hapi/validation/validator/FhirInstanceValidator.java b/hapi-fhir-validation/src/main/java/org/hl7/fhir/common/hapi/validation/validator/FhirInstanceValidator.java
index 70af4473f18..09dd738a9b7 100644
--- a/hapi-fhir-validation/src/main/java/org/hl7/fhir/common/hapi/validation/validator/FhirInstanceValidator.java
+++ b/hapi-fhir-validation/src/main/java/org/hl7/fhir/common/hapi/validation/validator/FhirInstanceValidator.java
@@ -35,6 +35,7 @@ public class FhirInstanceValidator extends BaseValidatorBridge implements IInsta
 	private boolean noBindingMsgSuppressed = false;
 	private volatile VersionSpecificWorkerContextWrapper myWrappedWorkerContext;
 	private boolean errorForUnknownProfiles = true;
+	private boolean myUnknownSystemsCauseErrors = true;
 	private boolean assumeValidRestReferences;
 	private List<String> myExtensionDomains = Collections.emptyList();
 	private IValidatorResourceFetcher validatorResourceFetcher;
@@ -132,6 +133,14 @@ public class FhirInstanceValidator extends BaseValidatorBridge implements IInsta
 		myBestPracticeWarningLevel = theBestPracticeWarningLevel;
 	}
 
+	public void setUnknownSystemsCauseErrors(boolean theUnknownSystemsCauseErrors) {
+		myUnknownSystemsCauseErrors = theUnknownSystemsCauseErrors;
+	}
+
+	public boolean isUnknownSystemsCauseErrors() {
+		return myUnknownSystemsCauseErrors;
+	}
+
 	/**
 	 * Returns the {@link IValidationSupport validation support} in use by this validator. Default is an instance of
 	 * DefaultProfileValidationSupport if the no-arguments constructor for this object was used.
@@ -229,6 +238,7 @@ public class FhirInstanceValidator extends BaseValidatorBridge implements IInsta
 				.setAnyExtensionsAllowed(isAnyExtensionsAllowed())
 				.setBestPracticeWarningLevel(getBestPracticeWarningLevel())
 				.setErrorForUnknownProfiles(isErrorForUnknownProfiles())
+				.setUnknownSystemsCauseErrors(isUnknownSystemsCauseErrors())
 				.setExtensionDomains(getExtensionDomains())
 				.setValidationPolicyAdvisor(validatorPolicyAdvisor)
 				.setNoTerminologyChecks(isNoTerminologyChecks())
diff --git a/hapi-fhir-validation/src/main/java/org/hl7/fhir/common/hapi/validation/validator/ValidatorWrapper.java b/hapi-fhir-validation/src/main/java/org/hl7/fhir/common/hapi/validation/validator/ValidatorWrapper.java
index c5ed37b5519..2528e5577ad 100644
--- a/hapi-fhir-validation/src/main/java/org/hl7/fhir/common/hapi/validation/validator/ValidatorWrapper.java
+++ b/hapi-fhir-validation/src/main/java/org/hl7/fhir/common/hapi/validation/validator/ValidatorWrapper.java
@@ -47,6 +47,7 @@ class ValidatorWrapper {
 	private boolean myAssumeValidRestReferences;
 	private boolean myNoExtensibleWarnings;
 	private boolean myNoBindingMsgSuppressed;
+	private boolean myUnknownSystemsCauseErrors;
 	private Collection<? extends String> myExtensionDomains;
 	private IValidatorResourceFetcher myValidatorResourceFetcher;
 	private IValidationPolicyAdvisor myValidationPolicyAdvisor;
@@ -82,6 +83,11 @@ class ValidatorWrapper {
 		return this;
 	}
 
+	public ValidatorWrapper setUnknownSystemsCauseErrors(boolean theUnknownSystemsCauseErrors) {
+		myUnknownSystemsCauseErrors = theUnknownSystemsCauseErrors;
+		return this;
+	}
+
 	public ValidatorWrapper setNoTerminologyChecks(boolean theNoTerminologyChecks) {
 		myNoTerminologyChecks = theNoTerminologyChecks;
 		return this;
@@ -129,6 +135,7 @@ class ValidatorWrapper {
 		v.setResourceIdRule(IdStatus.OPTIONAL);
 		v.setNoTerminologyChecks(myNoTerminologyChecks);
 		v.setErrorForUnknownProfiles(myErrorForUnknownProfiles);
+		v.setUnknownCodeSystemsCauseErrors(myUnknownSystemsCauseErrors);
 		v.getExtensionDomains().addAll(myExtensionDomains);
 		v.setFetcher(myValidatorResourceFetcher);
 		v.setPolicyAdvisor(myValidationPolicyAdvisor);
diff --git a/pom.xml b/pom.xml
index 0f562d546bd..81da15e82df 100644
--- a/pom.xml
+++ b/pom.xml
@@ -949,7 +949,7 @@
 	</licenses>
 
 	<properties>
-		<fhir_core_version>6.3.23</fhir_core_version>
+		<fhir_core_version>6.3.25</fhir_core_version>
 		<spotless_version>2.41.1</spotless_version>
 		<surefire_jvm_args>-Dfile.encoding=UTF-8 -Xmx2048m</surefire_jvm_args>