diff --git a/scm-webapp/src/main/java/sonia/scm/plugin/PluginProcessor.java b/scm-webapp/src/main/java/sonia/scm/plugin/PluginProcessor.java
index 11a7022dac..2f8589908a 100644
--- a/scm-webapp/src/main/java/sonia/scm/plugin/PluginProcessor.java
+++ b/scm-webapp/src/main/java/sonia/scm/plugin/PluginProcessor.java
@@ -84,6 +84,8 @@ public final class PluginProcessor
   /** Field description */
   private static final String DIRECTORY_INSTALLED = ".installed";
 
+  public static final String JAKARTA_COMPATIBLE = ".jakarta-compatible";
+
   /** Field description */
   private static final String DIRECTORY_METAINF = "META-INF";
 
@@ -175,9 +177,10 @@ public final class PluginProcessor
     logger.debug("found {} installed plugins", installedPlugins.size());
 
     for (ExplodedSmp installedPlugin : installedPlugins) {
-      if (installedPlugin.getPlugin().getScmVersion() < 3) {
+      if (shouldTransform(installedPlugin)) {
         logger.debug("start jakarta transformation of already installed plugin: {}", installedPlugin.getPlugin().getInformation().getName());
         PluginTransformer.transform(installedPlugin.getPath());
+        Files.createFile(installedPlugin.getPath().resolve(JAKARTA_COMPATIBLE));
       }
     }
 
@@ -185,9 +188,10 @@ public final class PluginProcessor
     logger.debug("finished installation of {} plugins", newlyInstalledPlugins.size());
 
     for (ExplodedSmp newInstalledSmp : newlyInstalledPlugins) {
-      if (newInstalledSmp.getPlugin().getScmVersion() < 3) {
+      if (shouldTransform(newInstalledSmp)) {
         logger.debug("start jakarta transformation of newly installed smp: {}", newInstalledSmp.getPlugin().getInformation().getName());
         PluginTransformer.transform(newInstalledSmp.getPath());
+        Files.createFile(newInstalledSmp.getPath().resolve(JAKARTA_COMPATIBLE));
       }
     }
 
@@ -209,6 +213,11 @@ public final class PluginProcessor
     return ImmutableSet.copyOf(wrappers);
   }
 
+  private boolean shouldTransform(ExplodedSmp newInstalledSmp) {
+    return newInstalledSmp.getPlugin().getScmVersion() < 3
+      && !newInstalledSmp.getPath().resolve(JAKARTA_COMPATIBLE).toFile().exists();
+  }
+
   private Set<ExplodedSmp> concat(Set<ExplodedSmp> installedPlugins, Set<ExplodedSmp> newlyInstalledPlugins) {
     // We first add all newly installed plugins,
     // after that we add the missing plugins, which are already installed.
diff --git a/scm-webapp/src/test/java/sonia/scm/plugin/PluginProcessorTest.java b/scm-webapp/src/test/java/sonia/scm/plugin/PluginProcessorTest.java
index bc474897fd..873c57dc10 100644
--- a/scm-webapp/src/test/java/sonia/scm/plugin/PluginProcessorTest.java
+++ b/scm-webapp/src/test/java/sonia/scm/plugin/PluginProcessorTest.java
@@ -35,6 +35,7 @@ import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.junit.jupiter.api.io.TempDir;
 import org.mockito.Mock;
+import org.mockito.MockedStatic;
 import org.mockito.Mockito;
 import org.mockito.junit.jupiter.MockitoExtension;
 import sonia.scm.lifecycle.classloading.ClassLoaderLifeCycle;
@@ -52,6 +53,9 @@ import java.util.zip.ZipOutputStream;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
 
 /**
  *
@@ -89,6 +93,10 @@ class PluginProcessorTest {
     new PluginResource("sonia/scm/plugin/scm-f-plugin-1.0.1.smp",
       "scm-f-plugin.smp", "scm-f-plugin:1.0.1");
 
+  private static final PluginResource PLUGIN_THIRD_MAJOR =
+    new PluginResource("sonia/scm/plugin/scm-thirdmajor-plugin.smp",
+      "scm-thirdmajor-plugin.smp", "scm-thirdmajor-plugin:1.0.0");
+
   private static final String PLUGIN_G = "scm-g-plugin";
   private static final String PLUGIN_H = "scm-h-plugin";
   private static final String PLUGIN_I = "scm-i-plugin";
@@ -185,7 +193,7 @@ class PluginProcessorTest {
     copySmp(PLUGIN_A);
 
     collectAndGetFirst();
-    Mockito.verify(pluginArchiveCleaner).cleanup(pluginDirectory.toPath().resolve(".installed"));
+    verify(pluginArchiveCleaner).cleanup(pluginDirectory.toPath().resolve(".installed"));
   }
 
   @Test
@@ -258,6 +266,37 @@ class PluginProcessorTest {
     assertThat(result).isEqualTo("hello again");
   }
 
+  @Test
+  void shouldTransformSecondMajorPlugin() throws Exception {
+    copySmps(PLUGIN_A);
+
+    Set<InstalledPlugin> plugins = collectPlugins();
+
+    assertThat(plugins.iterator().next().getDirectory().resolve(".jakarta-compatible")).exists();
+  }
+
+  @Test
+  void shouldNotTransformThirdMajorPlugin() throws Exception {
+    copySmps(PLUGIN_THIRD_MAJOR);
+
+    Set<InstalledPlugin> plugins = collectPlugins();
+
+    assertThat(plugins.iterator().next().getDirectory().resolve(".jakarta-compatible")).doesNotExist();
+  }
+
+  @Test
+  void shouldNotTransformAlreadyTransformedPlugins() throws Exception {
+    try (MockedStatic<PluginTransformer> staticMock = Mockito.mockStatic(PluginTransformer.class)) {
+      copySmps(PLUGIN_A);
+
+      collectPlugins();
+      collectPlugins();
+      collectPlugins();
+
+      staticMock.verify(() -> PluginTransformer.transform(any()), times(1));
+    }
+  }
+
   @Test
   @SuppressWarnings("UnstableApiUsage")
   void shouldCreatePluginWebResourceLoader() throws IOException {
diff --git a/scm-webapp/src/test/resources/sonia/scm/plugin/scm-thirdmajor-plugin.smp b/scm-webapp/src/test/resources/sonia/scm/plugin/scm-thirdmajor-plugin.smp
new file mode 100644
index 0000000000..a294774371
Binary files /dev/null and b/scm-webapp/src/test/resources/sonia/scm/plugin/scm-thirdmajor-plugin.smp differ