diff --git a/packages/compiler-cli/src/metadata/collector.ts b/packages/compiler-cli/src/metadata/collector.ts
index e2748ce9df..77611644f1 100644
--- a/packages/compiler-cli/src/metadata/collector.ts
+++ b/packages/compiler-cli/src/metadata/collector.ts
@@ -289,7 +289,7 @@ export class MetadataCollector {
          ts.TypeAliasDeclaration | ts.EnumDeclaration) => exportedIdentifierName(node.name);
 
 
-    // Predeclare classes and functions
+    // Pre-declare classes and functions
     ts.forEachChild(sourceFile, node => {
       switch (node.kind) {
         case ts.SyntaxKind.ClassDeclaration:
@@ -454,7 +454,7 @@ export class MetadataCollector {
                 };
               } else {
                 nextDefaultValue =
-                    recordEntry(errorSym('Unsuppported enum member name', member.name), node);
+                    recordEntry(errorSym('Unsupported enum member name', member.name), node);
               }
             }
             if (writtenMembers) {
diff --git a/packages/compiler-cli/src/metadata/evaluator.ts b/packages/compiler-cli/src/metadata/evaluator.ts
index 273db143c2..cf5c2ea269 100644
--- a/packages/compiler-cli/src/metadata/evaluator.ts
+++ b/packages/compiler-cli/src/metadata/evaluator.ts
@@ -356,9 +356,6 @@ export class Evaluator {
           }
         }
         const args = arrayOrEmpty(callExpression.arguments).map(arg => this.evaluateNode(arg));
-        if (!this.options.verboseInvalidExpression && args.some(isMetadataError)) {
-          return args.find(isMetadataError);
-        }
         if (this.isFoldable(callExpression)) {
           if (isMethodCallOf(callExpression, 'concat')) {
             const arrayValue = <MetadataValue[]>this.evaluateNode(
diff --git a/packages/compiler-cli/test/metadata/collector_spec.ts b/packages/compiler-cli/test/metadata/collector_spec.ts
index 34ca4a4979..9d4bbf7e0e 100644
--- a/packages/compiler-cli/test/metadata/collector_spec.ts
+++ b/packages/compiler-cli/test/metadata/collector_spec.ts
@@ -1054,10 +1054,20 @@ describe('Collector', () => {
       expect(metadata.metadata.MyComponent).toEqual({
         __symbolic: 'class',
         decorators: [{
-          __symbolic: 'error',
-          message: 'Expression form not supported',
-          line: 5,
-          character: 55
+          __symbolic: 'call',
+          expression: {
+            __symbolic: 'reference',
+            module: '@angular/core',
+            name: 'Component',
+            line: 4,
+            character: 9
+          },
+          arguments: [{
+            __symbolic: 'error',
+            message: 'Expression form not supported',
+            line: 5,
+            character: 55
+          }]
         }]
       });
     });
diff --git a/packages/compiler-cli/test/ngc_spec.ts b/packages/compiler-cli/test/ngc_spec.ts
index 65bc967120..dafa6fe3dd 100644
--- a/packages/compiler-cli/test/ngc_spec.ts
+++ b/packages/compiler-cli/test/ngc_spec.ts
@@ -1698,6 +1698,40 @@ describe('ngc transformer command-line', () => {
       expect(messages[0]).toContain(`is imported recursively by the module 'MyFaultyImport`);
     });
 
+    // Regression test for #21273
+    it('should not report errors for unknown property annotations', () => {
+      write('src/tsconfig.json', `{
+        "extends": "../tsconfig-base.json",
+        "files": ["test-module.ts"]
+      }`);
+
+      write('src/test-decorator.ts', `
+        export function Convert(p: any): any {
+          // Make sur this doesn't look like a macro function
+          var r = p;
+          return r;
+        }
+      `);
+      write('src/test-module.ts', `
+        import {Component, Input, NgModule} from '@angular/core';
+        import {Convert} from './test-decorator';
+
+        @Component({template: '{{name}}'})
+        export class TestComponent {
+          @Input() @Convert(convert) name: string;
+        }
+
+        function convert(n: any) { return n; }
+
+        @NgModule({declarations: [TestComponent]})
+        export class TestModule {}
+      `);
+      const messages: string[] = [];
+      expect(
+          main(['-p', path.join(basePath, 'src/tsconfig.json')], message => messages.push(message)))
+          .toBe(0, `Compile failed:\n ${messages.join('\n    ')}`);
+    });
+
     it('should allow using 2 classes with the same name in declarations with noEmitOnError=true',
        () => {
          write('src/tsconfig.json', `{
diff --git a/packages/compiler/test/aot/static_reflector_spec.ts b/packages/compiler/test/aot/static_reflector_spec.ts
index 0d13a2bd25..eb6f636400 100644
--- a/packages/compiler/test/aot/static_reflector_spec.ts
+++ b/packages/compiler/test/aot/static_reflector_spec.ts
@@ -364,7 +364,8 @@ describe('StaticReflector', () => {
       const classData: any = moduleMetadata['InvalidMetadata'];
       expect(classData).toBeDefined();
       simplify(
-          reflector.getStaticSymbol('/tmp/src/invalid-metadata.ts', ''), classData.decorators[0]);
+          reflector.getStaticSymbol('/tmp/src/invalid-metadata.ts', ''),
+          classData.decorators[0].arguments);
     } catch (e) {
       expect(e.position).toBeDefined();
       threw = true;