diff --git a/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt b/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
index 84598acf2a0..4d2f1b8604e 100644
--- a/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
+++ b/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
@@ -477,6 +477,7 @@ object DIAGNOSTICS_LIST : DiagnosticList() {
             parameter<ConeKotlinType>("varargParameterType")
         }
         val VALUE_PARAMETER_WITH_NO_TYPE_ANNOTATION by error<FirSourceElement, KtParameter>()
+        val CANNOT_INFER_PARAMETER_TYPE by error<FirSourceElement, KtParameter>()
     }
 
     val FUN_INTERFACES by object : DiagnosticGroup("Fun interfaces") {
diff --git a/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt b/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
index de3d6770fe3..1682362fa1a 100644
--- a/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
+++ b/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
@@ -295,6 +295,7 @@ object FirErrors {
     val MULTIPLE_VARARG_PARAMETERS by error0<FirSourceElement, KtParameter>(SourceElementPositioningStrategies.PARAMETER_VARARG_MODIFIER)
     val FORBIDDEN_VARARG_PARAMETER_TYPE by error1<FirSourceElement, KtParameter, ConeKotlinType>(SourceElementPositioningStrategies.PARAMETER_VARARG_MODIFIER)
     val VALUE_PARAMETER_WITH_NO_TYPE_ANNOTATION by error0<FirSourceElement, KtParameter>()
+    val CANNOT_INFER_PARAMETER_TYPE by error0<FirSourceElement, KtParameter>()
 
     // Fun interfaces
     val FUN_INTERFACE_CONSTRUCTOR_REFERENCE by error0<FirSourceElement, KtExpression>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)
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 e990e6555e8..588e85c9a99 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
@@ -49,6 +49,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.BREAK_OR_CONTINUE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CALLABLE_REFERENCE_LHS_NOT_A_CLASS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CALLABLE_REFERENCE_TO_ANNOTATION_CONSTRUCTOR
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CANNOT_CHANGE_ACCESS_PRIVILEGE
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CANNOT_INFER_PARAMETER_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CANNOT_WEAKEN_ACCESS_PRIVILEGE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CAN_BE_REPLACED_WITH_OPERATOR_ASSIGNMENT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CAN_BE_VAL
@@ -685,6 +686,7 @@ class FirDefaultErrorMessages : DefaultErrorMessages.Extension {
             map.put(MULTIPLE_VARARG_PARAMETERS, "Multiple vararg-parameters are prohibited")
             map.put(FORBIDDEN_VARARG_PARAMETER_TYPE, "Forbidden vararg parameter type: {0}", RENDER_TYPE)
             map.put(VALUE_PARAMETER_WITH_NO_TYPE_ANNOTATION, "A type annotation is required on a value parameter")
+            map.put(CANNOT_INFER_PARAMETER_TYPE, "cannot infer a type for this parameter. Please specify it explicitly.")
 
             // Fun interfaces
             map.put(FUN_INTERFACE_CONSTRUCTOR_REFERENCE, "Functional interface constructor references are prohibited")
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/coneDiagnosticToFirDiagnostic.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/coneDiagnosticToFirDiagnostic.kt
index 80af52209c4..9f02fffc467 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/coneDiagnosticToFirDiagnostic.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/coneDiagnosticToFirDiagnostic.kt
@@ -176,6 +176,7 @@ private fun ConeSimpleDiagnostic.getFactory(): FirDiagnosticFactory0<FirSourceEl
         DiagnosticKind.NotLoopLabel -> FirErrors.NOT_A_LOOP_LABEL
         DiagnosticKind.VariableExpected -> FirErrors.VARIABLE_EXPECTED
         DiagnosticKind.ValueParameterWithNoTypeAnnotation -> FirErrors.VALUE_PARAMETER_WITH_NO_TYPE_ANNOTATION
+        DiagnosticKind.CannotInferParameterType -> FirErrors.CANNOT_INFER_PARAMETER_TYPE
         DiagnosticKind.UnknownCallableKind -> FirErrors.UNKNOWN_CALLABLE_KIND
         DiagnosticKind.IllegalProjectionUsage -> FirErrors.ILLEGAL_PROJECTION_USAGE
         DiagnosticKind.MissingStdlibClass -> FirErrors.MISSING_STDLIB_CLASS
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/InferenceUtils.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/InferenceUtils.kt
index bff94a0be79..c95a158e7d5 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/InferenceUtils.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/InferenceUtils.kt
@@ -9,6 +9,8 @@ import org.jetbrains.kotlin.builtins.functions.FunctionClassKind
 import org.jetbrains.kotlin.fir.*
 import org.jetbrains.kotlin.fir.declarations.FirAnonymousFunction
 import org.jetbrains.kotlin.fir.declarations.FirClass
+import org.jetbrains.kotlin.fir.diagnostics.ConeSimpleDiagnostic
+import org.jetbrains.kotlin.fir.diagnostics.DiagnosticKind
 import org.jetbrains.kotlin.fir.expressions.FirReturnExpression
 import org.jetbrains.kotlin.fir.resolve.*
 import org.jetbrains.kotlin.fir.resolve.calls.Candidate
@@ -201,30 +203,25 @@ fun ConeKotlinType.isKClassType(): Boolean {
     return classId == StandardClassIds.KClass
 }
 
+private fun ConeTypeProjection.typeOrDefault(default: ConeKotlinType): ConeKotlinType =
+    when (this) {
+        is ConeKotlinTypeProjection -> type
+        is ConeStarProjection -> default
+    }
+
 fun ConeKotlinType.receiverType(session: FirSession): ConeKotlinType? {
     if (!isBuiltinFunctionalType(session) || !isExtensionFunctionType(session)) return null
-    return when (val projection = fullyExpandedType(session).typeArguments.first()) {
-        is ConeKotlinTypeProjection -> projection.type
-        is ConeStarProjection -> session.builtinTypes.nothingType.type
-    }
+    return fullyExpandedType(session).typeArguments.first().typeOrDefault(session.builtinTypes.nothingType.type)
 }
 
 fun ConeKotlinType.returnType(session: FirSession): ConeKotlinType {
     require(this is ConeClassLikeType)
-    return when (val projection = fullyExpandedType(session).typeArguments.last()) {
-        is ConeKotlinTypeProjection -> projection.type
-        is ConeStarProjection -> session.builtinTypes.nullableAnyType.type
-    }
+    return fullyExpandedType(session).typeArguments.last().typeOrDefault(session.builtinTypes.nullableAnyType.type)
 }
 
 fun ConeKotlinType.valueParameterTypesIncludingReceiver(session: FirSession): List<ConeKotlinType> {
     require(this is ConeClassLikeType)
-    return fullyExpandedType(session).typeArguments.dropLast(1).map {
-        when (it) {
-            is ConeKotlinTypeProjection -> it.type
-            is ConeStarProjection -> session.builtinTypes.nothingType.type
-        }
-    }
+    return fullyExpandedType(session).typeArguments.dropLast(1).map { it.typeOrDefault(session.builtinTypes.nothingType.type) }
 }
 
 val FirAnonymousFunction.returnType: ConeKotlinType? get() = returnTypeRef.coneTypeSafe()
@@ -261,7 +258,7 @@ fun extractLambdaInfoFromFunctionalType(
             session.builtinTypes.unitType.type
         else
             argument.returnType ?: expectedType.returnType(session)
-    // `fun (x: T) = ...` and `fun T.() = ...` are both instances of `T.() -> V`; `fun () = ...` is not.
+    // `fun (x: T) = ...` and `fun T.() = ...` are both instances of `T.() -> V` and `(T) -> V`; `fun () = ...` is not.
     // For lambdas, the existence of the receiver is always implied by the expected type, and a value parameter
     // can never fill its role.
     val receiverType = if (argument.isLambda) expectedType.receiverType(session) else argument.receiverType
@@ -272,7 +269,8 @@ fun extractLambdaInfoFromFunctionalType(
         expectedParameters // Infer existence of a parameter named `it` of an appropriate type.
     } else {
         argument.valueParameters.mapIndexed { index, parameter ->
-            parameter.returnTypeRef.coneTypeSafe() ?: expectedParameters.getOrNull(index) ?: session.builtinTypes.nothingType.type
+            parameter.returnTypeRef.coneTypeSafe() ?: expectedParameters.getOrNull(index)
+                ?: ConeClassErrorType(ConeSimpleDiagnostic("Cannot infer type for parameter ${parameter.name}", DiagnosticKind.CannotInferParameterType))
         }
     }
 
diff --git a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/diagnostics/ConeSimpleDiagnostic.kt b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/diagnostics/ConeSimpleDiagnostic.kt
index 203bbfb263b..09984b6c3b8 100644
--- a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/diagnostics/ConeSimpleDiagnostic.kt
+++ b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/diagnostics/ConeSimpleDiagnostic.kt
@@ -27,6 +27,7 @@ enum class DiagnosticKind {
     Java,
     SuperNotAllowed,
     ValueParameterWithNoTypeAnnotation,
+    CannotInferParameterType,
     UnknownCallableKind,
     IllegalProjectionUsage,
     MissingStdlibClass,
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt
index 7c59608da7e..8b71e08e929 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt
+++ b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt
@@ -1338,6 +1338,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.CANNOT_INFER_PARAMETER_TYPE) { firDiagnostic ->
+        CannotInferParameterTypeImpl(
+            firDiagnostic as FirPsiDiagnostic<*>,
+            token,
+        )
+    }
     add(FirErrors.FUN_INTERFACE_CONSTRUCTOR_REFERENCE) { firDiagnostic ->
         FunInterfaceConstructorReferenceImpl(
             firDiagnostic as FirPsiDiagnostic<*>,
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt
index 747ba79e83c..2c4587defe9 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt
+++ b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt
@@ -949,6 +949,10 @@ sealed class KtFirDiagnostic<PSI: PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = ValueParameterWithNoTypeAnnotation::class
     }
 
+    abstract class CannotInferParameterType : KtFirDiagnostic<KtParameter>() {
+        override val diagnosticClass get() = CannotInferParameterType::class
+    }
+
     abstract class FunInterfaceConstructorReference : KtFirDiagnostic<KtExpression>() {
         override val diagnosticClass get() = FunInterfaceConstructorReference::class
     }
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
index 00ac575bc0a..fc81f8051d2 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
+++ b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
@@ -1529,6 +1529,13 @@ internal class ValueParameterWithNoTypeAnnotationImpl(
     override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
 }
 
+internal class CannotInferParameterTypeImpl(
+    firDiagnostic: FirPsiDiagnostic<*>,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.CannotInferParameterType(), KtAbstractFirDiagnostic<KtParameter> {
+    override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
+}
+
 internal class FunInterfaceConstructorReferenceImpl(
     firDiagnostic: FirPsiDiagnostic<*>,
     override val token: ValidityToken,