diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberFunctionChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberFunctionChecker.kt
index 7596902d254..7046416221f 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberFunctionChecker.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberFunctionChecker.kt
@@ -39,10 +39,10 @@ object FirMemberFunctionChecker : FirRegularClassChecker() {
         val isAbstract = function.isAbstract || hasAbstractModifier
         if (isAbstract) {
             if (!containingDeclaration.canHaveAbstractDeclaration) {
-                reporter.report(source, FirErrors.ABSTRACT_FUNCTION_IN_NON_ABSTRACT_CLASS)
+                reporter.report(FirErrors.ABSTRACT_FUNCTION_IN_NON_ABSTRACT_CLASS.on(source, function, containingDeclaration))
             }
             if (function.hasBody) {
-                reporter.report(source, FirErrors.ABSTRACT_FUNCTION_WITH_BODY)
+                reporter.report(FirErrors.ABSTRACT_FUNCTION_WITH_BODY.on(source, function))
             }
         }
         val isInsideExpectClass = isInsideExpectClass(containingDeclaration, context)
@@ -51,13 +51,13 @@ object FirMemberFunctionChecker : FirRegularClassChecker() {
         if (!function.hasBody) {
             if (containingDeclaration.isInterface) {
                 if (Visibilities.isPrivate(function.visibility)) {
-                    reporter.report(source, FirErrors.PRIVATE_FUNCTION_WITH_NO_BODY)
+                    reporter.report(FirErrors.PRIVATE_FUNCTION_WITH_NO_BODY.on(source, function))
                 }
                 if (!isInsideExpectClass && !hasAbstractModifier && hasOpenModifier) {
                     reporter.report(source, FirErrors.REDUNDANT_OPEN_IN_INTERFACE)
                 }
             } else if (!isInsideExpectClass && !hasAbstractModifier && !isExternal) {
-                reporter.report(FirErrors.NON_ABSTRACT_FUNCTION_WITH_NO_BODY.on(source, function.symbol))
+                reporter.report(FirErrors.NON_ABSTRACT_FUNCTION_WITH_NO_BODY.on(source, function))
             }
         }
     }
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDefaultErrorMessages.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDefaultErrorMessages.kt
index c254376d305..4b3e444d388 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDefaultErrorMessages.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDefaultErrorMessages.kt
@@ -14,6 +14,8 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.SYMB
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.SYMBOLS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.TO_STRING
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ABSTRACT_DELEGATED_PROPERTY
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ABSTRACT_FUNCTION_IN_NON_ABSTRACT_CLASS
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ABSTRACT_FUNCTION_WITH_BODY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ABSTRACT_PROPERTY_IN_NON_ABSTRACT_CLASS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ABSTRACT_PROPERTY_WITH_GETTER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ABSTRACT_PROPERTY_WITH_INITIALIZER
@@ -71,6 +73,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LOCAL_OBJECT_NOT_
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MANY_COMPANION_OBJECTS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MISSING_VAL_ON_ANNOTATION_PARAMETER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NONE_APPLICABLE
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NON_ABSTRACT_FUNCTION_WITH_NO_BODY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NON_PRIVATE_CONSTRUCTOR_IN_ENUM
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NON_PRIVATE_CONSTRUCTOR_IN_SEALED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NOT_AN_ANNOTATION_CLASS
@@ -82,6 +85,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NULLABLE_TYPE_OF_
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.OTHER_ERROR
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRIMARY_CONSTRUCTOR_DELEGATION_CALL_EXPECTED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRIMARY_CONSTRUCTOR_REQUIRED_FOR_DATA_CLASS
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRIVATE_FUNCTION_WITH_NO_BODY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRIVATE_PROPERTY_IN_INTERFACE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRIVATE_SETTER_FOR_ABSTRACT_PROPERTY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRIVATE_SETTER_FOR_OPEN_PROPERTY
@@ -97,6 +101,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_CALL_OF
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_EXPLICIT_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_MODALITY_MODIFIER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_MODIFIER
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_OPEN_IN_INTERFACE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_RETURN_UNIT_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_SETTER_PARAMETER_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_SINGLE_EXPRESSION_STRING_TEMPLATE
@@ -263,6 +268,7 @@ class FirDefaultErrorMessages : DefaultErrorMessages.Extension {
             map.put(REDUNDANT_MODIFIER, "Modifier ''{0}'' is redundant because ''{1}'' is present", TO_STRING, TO_STRING)
             map.put(DEPRECATED_MODIFIER_PAIR, "Modifier ''{0}'' is deprecated in presence of ''{1}''", TO_STRING, TO_STRING)
             map.put(INCOMPATIBLE_MODIFIERS, "Modifier ''{0}'' is incompatible with ''{1}''", TO_STRING, TO_STRING)
+            map.put(REDUNDANT_OPEN_IN_INTERFACE, "Modifier 'open' is redundant for abstract interface members")
 
             // Applicability
             map.put(NONE_APPLICABLE, "None of the following functions are applicable: {0}", SYMBOLS)
@@ -336,6 +342,17 @@ class FirDefaultErrorMessages : DefaultErrorMessages.Extension {
                 TO_STRING
             )
 
+            // Functions
+            map.put(
+                ABSTRACT_FUNCTION_IN_NON_ABSTRACT_CLASS,
+                "Abstract function ''{0}'' in non-abstract class ''{1}''",
+                DECLARATION_NAME,
+                DECLARATION_NAME
+            )
+            map.put(ABSTRACT_FUNCTION_WITH_BODY, "A function ''{0}'' with body cannot be abstract", DECLARATION_NAME)
+            map.put(NON_ABSTRACT_FUNCTION_WITH_NO_BODY, "Function ''{0}'' without a body must be abstract", DECLARATION_NAME)
+            map.put(PRIVATE_FUNCTION_WITH_NO_BODY, "Function ''{0}'' without body cannot be private", DECLARATION_NAME)
+
             // Properties & accessors
             map.put(
                 ABSTRACT_PROPERTY_IN_NON_ABSTRACT_CLASS,
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
index 4fa70ac8702..dd95a824702 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
@@ -148,10 +148,10 @@ object FirErrors {
     val LOCAL_INTERFACE_NOT_ALLOWED by error1<FirSourceElement, KtNamedDeclaration, Name>(SourceElementPositioningStrategies.DECLARATION_NAME)
 
     // Functions
-    val ABSTRACT_FUNCTION_IN_NON_ABSTRACT_CLASS by error0<FirSourceElement, KtModifierListOwner>(SourceElementPositioningStrategies.MODALITY_MODIFIER)
-    val ABSTRACT_FUNCTION_WITH_BODY by error0<FirSourceElement, KtModifierListOwner>(SourceElementPositioningStrategies.MODALITY_MODIFIER)
-    val NON_ABSTRACT_FUNCTION_WITH_NO_BODY by error1<FirSourceElement, PsiElement, FirFunctionSymbol<*>>()
-    val PRIVATE_FUNCTION_WITH_NO_BODY by error0<FirSourceElement, KtModifierListOwner>(SourceElementPositioningStrategies.VISIBILITY_MODIFIER)
+    val ABSTRACT_FUNCTION_IN_NON_ABSTRACT_CLASS by error2<FirSourceElement, KtFunction, FirMemberDeclaration, FirMemberDeclaration>(SourceElementPositioningStrategies.MODALITY_MODIFIER)
+    val ABSTRACT_FUNCTION_WITH_BODY by error1<FirSourceElement, KtFunction, FirMemberDeclaration>(SourceElementPositioningStrategies.MODALITY_MODIFIER)
+    val NON_ABSTRACT_FUNCTION_WITH_NO_BODY by error1<FirSourceElement, KtFunction, FirMemberDeclaration>(SourceElementPositioningStrategies.DECLARATION_SIGNATURE)
+    val PRIVATE_FUNCTION_WITH_NO_BODY by error1<FirSourceElement, KtFunction, FirMemberDeclaration>(SourceElementPositioningStrategies.VISIBILITY_MODIFIER)
 
     // Properties & accessors
     val ABSTRACT_PROPERTY_IN_NON_ABSTRACT_CLASS by error2<FirSourceElement, KtModifierListOwner, FirMemberDeclaration, FirMemberDeclaration>(SourceElementPositioningStrategies.MODALITY_MODIFIER)