diff --git a/src/Framework/Framework/Resources/Scripts/global-declarations.ts b/src/Framework/Framework/Resources/Scripts/global-declarations.ts
index 848700e9fe..e875e05ef8 100644
--- a/src/Framework/Framework/Resources/Scripts/global-declarations.ts
+++ b/src/Framework/Framework/Resources/Scripts/global-declarations.ts
@@ -248,16 +248,19 @@ type TypeMap = {
 }
 
 type DynamicTypeMetadata = {
+    debugName?: string,
     type: "dynamic"
 }
 
 type ObjectTypeMetadata = {
     type: "object",
+    debugName?: string,
     properties: { [prop: string]: PropertyMetadata }
 }
 
 type EnumTypeMetadata = {
     type: "enum",
+    debugName?: string,
     values: { [name: string]: number },
     isFlags?: boolean
 }
diff --git a/src/Framework/Framework/Resources/Scripts/metadata/coercer.ts b/src/Framework/Framework/Resources/Scripts/metadata/coercer.ts
index a7e58b4bf9..6d83ed6e8b 100644
--- a/src/Framework/Framework/Resources/Scripts/metadata/coercer.ts
+++ b/src/Framework/Framework/Resources/Scripts/metadata/coercer.ts
@@ -3,7 +3,7 @@ import { CoerceError } from "../shared-classes";
 import { keys } from "../utils/objects";
 import { tryCoerceEnum } from "./enums";
 import { primitiveTypes } from "./primitiveTypes";
-import { getObjectTypeInfo, getTypeInfo } from "./typeMap";
+import { formatTypeName, getObjectTypeInfo, getTypeInfo } from "./typeMap";
 
 /**
  * Validates type of value
@@ -45,7 +45,7 @@ export function tryCoerce(value: any, type: TypeDefinition | null | undefined, o
                 }
             }
         }
-        return new CoerceError(`Unsupported type metadata ${JSON.stringify(type)}!`);
+        return new CoerceError(`Unsupported type metadata ${formatTypeName(type)}!`);
     }
 
     const result = core();
@@ -100,7 +100,7 @@ function tryCoerceArray(value: any, innerType: TypeDefinition, originalValue: an
             return { value: items, wasCoerced: true };
         }
     }
-    return new CoerceError(`Value '${JSON.stringify(value)}' is not an array of type '${JSON.stringify(innerType)}'.`);
+    return new CoerceError(`Value '${JSON.stringify(value)}' is not an array of type '${formatTypeName(innerType)}'.`);
 }
 
 function tryCoercePrimitiveType(value: any, type: string): CoerceResult {
diff --git a/src/Framework/Framework/Resources/Scripts/metadata/typeMap.ts b/src/Framework/Framework/Resources/Scripts/metadata/typeMap.ts
index cb6052aa8c..63ed224006 100644
--- a/src/Framework/Framework/Resources/Scripts/metadata/typeMap.ts
+++ b/src/Framework/Framework/Resources/Scripts/metadata/typeMap.ts
@@ -63,3 +63,28 @@ export function areObjectTypesEqual(currentValue: any, newVal: any): boolean {
     }
     return false;
 }
+
+
+export function formatTypeName(type: TypeDefinition, prefix = "", suffix = ""): string {
+    if (!compileConstants.debug)
+        return JSON.stringify(type)
+
+    if (typeof type === "string") {
+        let debugName = types[type]?.debugName
+        if (debugName)
+            return `${prefix}${debugName}${suffix} (${prefix}${type}${suffix})`
+        else
+            return prefix + type + suffix
+    }
+    if (Array.isArray(type)) {
+        return formatTypeName(type[0], prefix, "[]" + suffix)
+    }
+    if (type.type == "nullable") {
+        return formatTypeName(type.inner, prefix, "?" + suffix)
+    }
+    if (type.type == "dynamic") {
+        return prefix + "dynamic" + suffix
+    }
+    const typeCheck: never = type
+    return undefined as any
+}
diff --git a/src/Framework/Framework/Resources/Scripts/state-manager.ts b/src/Framework/Framework/Resources/Scripts/state-manager.ts
index 3dc584242b..737ecdd02f 100644
--- a/src/Framework/Framework/Resources/Scripts/state-manager.ts
+++ b/src/Framework/Framework/Resources/Scripts/state-manager.ts
@@ -3,7 +3,7 @@
 import { createArray, defineConstantProperty, isPrimitive, keys } from "./utils/objects";
 import { DotvvmEvent } from "./events";
 import { extendToObservableArrayIfRequired } from "./serialization/deserialize"
-import { areObjectTypesEqual, getObjectTypeInfo } from "./metadata/typeMap";
+import { areObjectTypesEqual, formatTypeName, getObjectTypeInfo } from "./metadata/typeMap";
 import { coerce } from "./metadata/coercer";
 import { patchViewModel } from "./postback/updater";
 import { hackInvokeNotifySubscribers } from "./utils/knockout";
@@ -166,7 +166,7 @@ class FakeObservableObject<T extends object> implements UpdatableObjectExtension
                             }
                         }
                     } else if (!isDynamic && p.indexOf("$") !== 0) {
-                        logWarning("state-manager", `Unknown property '${p}' set on an object of type ${typeId}.`);
+                        logWarning("state-manager", `Unknown property '${p}' set on an object of type ${formatTypeName(typeId)}.`);
                     }
 
                     this[internalPropCache][p] = newObs
diff --git a/src/Framework/Framework/Resources/Scripts/tests/coercer.test.ts b/src/Framework/Framework/Resources/Scripts/tests/coercer.test.ts
index 2d99a2a3ee..81e252ddef 100644
--- a/src/Framework/Framework/Resources/Scripts/tests/coercer.test.ts
+++ b/src/Framework/Framework/Resources/Scripts/tests/coercer.test.ts
@@ -1,4 +1,5 @@
 import { tryCoerce } from "../metadata/coercer"
+import { formatTypeName } from "../metadata/typeMap";
 import { initDotvvm } from "./helper";
 
 initDotvvm({
@@ -9,6 +10,7 @@ initDotvvm({
     typeMetadata: {
         t1: {
             type: "object",
+            debugName: "MyType1",
             properties: {
                 a: {
                     type: "String"
@@ -607,3 +609,13 @@ test("dynamic - valid, object of unknown type, nested known object", () => {
     expect(result.wasCoerced).toBeFalsy();
     expect(result.value).toEqual({ inner: { $type: "t1", a: "aa" } });
 })
+
+test("formatTypeName", () => {
+    expect(formatTypeName("t1")).toBe("MyType1 (t1)");
+    expect(formatTypeName("t2")).toBe("t2");
+    expect(formatTypeName([ "t1" ])).toBe("MyType1[] (t1[])");
+    expect(formatTypeName([ "t2" ])).toBe("t2[]");
+    expect(formatTypeName({ type: "nullable", inner: "t1" })).toBe("MyType1? (t1?)");
+    expect(formatTypeName({ type: "nullable", inner: "t2" })).toBe("t2?");
+    expect(formatTypeName([ { type:"nullable", inner: [ [ "t1" ] ] }])).toBe("MyType1[][]?[] (t1[][]?[])");
+})