diff --git a/scm-core/src/main/java/sonia/scm/repository/spi/CannotDeleteDefaultBranchException.java b/scm-core/src/main/java/sonia/scm/repository/spi/CannotDeleteDefaultBranchException.java
new file mode 100644
index 0000000000..0053d5384a
--- /dev/null
+++ b/scm-core/src/main/java/sonia/scm/repository/spi/CannotDeleteDefaultBranchException.java
@@ -0,0 +1,19 @@
+package sonia.scm.repository.spi;
+
+import sonia.scm.ContextEntry;
+import sonia.scm.ExceptionWithContext;
+import sonia.scm.repository.Repository;
+
+public class CannotDeleteDefaultBranchException extends ExceptionWithContext {
+
+  public static final String CODE = "78RhWxTIw1";
+
+  public CannotDeleteDefaultBranchException(Repository repository, String branchName) {
+    super(ContextEntry.ContextBuilder.entity("Branch", branchName).in(repository).build(), "default branch cannot be deleted");
+  }
+
+  @Override
+  public String getCode() {
+    return CODE;
+  }
+}
diff --git a/scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitBranchCommand.java b/scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitBranchCommand.java
index 3650f3c54e..fd3c25cf39 100644
--- a/scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitBranchCommand.java
+++ b/scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitBranchCommand.java
@@ -33,6 +33,7 @@
 package sonia.scm.repository.spi;
 
 import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.errors.CannotDeleteCurrentBranchException;
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.lib.Ref;
 import sonia.scm.event.ScmEventBus;
@@ -94,6 +95,8 @@ public class GitBranchCommand extends AbstractGitCommand implements BranchComman
         .setForce(true)
         .call();
       eventBus.post(new PostReceiveRepositoryHookEvent(hookEvent));
+    } catch (CannotDeleteCurrentBranchException e) {
+      throw new CannotDeleteDefaultBranchException(context.getRepository(), branchName);
     } catch (GitAPIException | IOException ex) {
       throw new InternalRepositoryException(entity(context.getRepository()), String.format("Could not delete branch: %s", branchName));
     }
diff --git a/scm-plugins/scm-git-plugin/src/test/java/sonia/scm/repository/spi/GitBranchCommandTest.java b/scm-plugins/scm-git-plugin/src/test/java/sonia/scm/repository/spi/GitBranchCommandTest.java
index d9b23f6c7a..8bfb0d16ad 100644
--- a/scm-plugins/scm-git-plugin/src/test/java/sonia/scm/repository/spi/GitBranchCommandTest.java
+++ b/scm-plugins/scm-git-plugin/src/test/java/sonia/scm/repository/spi/GitBranchCommandTest.java
@@ -8,7 +8,6 @@ import org.mockito.invocation.InvocationOnMock;
 import org.mockito.junit.MockitoJUnitRunner;
 import sonia.scm.event.ScmEventBus;
 import sonia.scm.repository.Branch;
-import sonia.scm.repository.InternalRepositoryException;
 import sonia.scm.repository.PostReceiveRepositoryHookEvent;
 import sonia.scm.repository.PreReceiveRepositoryHookEvent;
 import sonia.scm.repository.api.BranchRequest;
@@ -78,9 +77,9 @@ public class GitBranchCommandTest extends AbstractGitCommandTestBase {
   }
 
   @Test
-  public void shouldThrowInternalRepositoryException() {
+  public void shouldThrowExceptionWhenDeletingDefaultBranch() {
     String branchToBeDeleted = "master";
-    assertThrows(InternalRepositoryException.class, () -> createCommand().deleteOrClose(branchToBeDeleted));
+    assertThrows(CannotDeleteDefaultBranchException.class, () -> createCommand().deleteOrClose(branchToBeDeleted));
   }
 
   private GitBranchCommand createCommand() {
diff --git a/scm-webapp/src/main/resources/locales/de/plugins.json b/scm-webapp/src/main/resources/locales/de/plugins.json
index fe97d296c4..9d25485fa9 100644
--- a/scm-webapp/src/main/resources/locales/de/plugins.json
+++ b/scm-webapp/src/main/resources/locales/de/plugins.json
@@ -187,6 +187,10 @@
     "6eRhF9gU41": {
       "displayName": "Nicht unterstützte Merge-Strategie",
       "description": "Die gewählte Merge-Strategie wird von dem Repository nicht unterstützt."
+    },
+    "78RhWxTIw1": {
+      "displayName": "Der Default-Branch kann nicht gelöscht werden",
+      "description": "Der Default-Branch kann nicht gelöscht werden. Bitte wählen Sie zuerst einen neuen Default-Branch."
     }
   },
   "namespaceStrategies": {
diff --git a/scm-webapp/src/main/resources/locales/en/plugins.json b/scm-webapp/src/main/resources/locales/en/plugins.json
index 27171374c9..cde0cbb9d4 100644
--- a/scm-webapp/src/main/resources/locales/en/plugins.json
+++ b/scm-webapp/src/main/resources/locales/en/plugins.json
@@ -187,6 +187,10 @@
     "6eRhF9gU41": {
       "displayName": "Merge strategy not supported",
       "description": "The selected merge strategy is not supported by the repository."
+    },
+    "78RhWxTIw1": {
+      "displayName": "Default branch cannot be deleted",
+      "description": "The default branch of a repository cannot be deleted. Please select another default branch first."
     }
   },
   "namespaceStrategies": {