diff --git a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting7/ExtensionMethodSyntax.java b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting7/ExtensionMethodSyntax.java
index 63411f68c522..a5e0917301b6 100644
--- a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting7/ExtensionMethodSyntax.java
+++ b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting7/ExtensionMethodSyntax.java
@@ -1,7 +1,7 @@
 interface I {
-  void m1() <warning descr="Deprecated extension method syntax">default</warning> { }
+  void m1() <error descr="Deprecated extension method syntax">default</error> { }
 
-  default void m2() <warning descr="Deprecated extension method syntax">default</warning> { }
+  default void m2() <error descr="Deprecated extension method syntax">default</error> { }
 
   @SuppressWarnings("extensionSyntax")
   void m3() default { }
diff --git a/resources/src/META-INF/IdeaPlugin.xml b/resources/src/META-INF/IdeaPlugin.xml
index a13e2d1c0354..4dae021bbebc 100644
--- a/resources/src/META-INF/IdeaPlugin.xml
+++ b/resources/src/META-INF/IdeaPlugin.xml
@@ -468,7 +468,7 @@
                      enabledByDefault="true" level="WARNING"
                      implementationClass="com.intellij.codeInspection.deprecation.DeprecationInspection"/>
     <localInspection language="JAVA" suppressId="extensionSyntax" bundle="messages.InspectionsBundle" key="deprecated.defender.syntax.description"
-                     groupName="" enabledByDefault="true" level="WARNING"
+                     groupName="" enabledByDefault="true" level="ERROR"
                      implementationClass="com.intellij.codeInspection.deprecation.DeprecatedDefenderSyntaxInspection"/>
     <localInspection language="XML" shortName="DeprecatedClassUsageInspection" displayName="Deprecated API usage in XML" groupName="XML"
                      enabledByDefault="true" level="WARNING" implementationClass="com.intellij.util.xml.DeprecatedClassUsageInspection"/>