diff --git a/modules/jooby-test/src/main/java/io/jooby/test/MockRouter.java b/modules/jooby-test/src/main/java/io/jooby/test/MockRouter.java
index 6c9564bb9a..0cfd91ce15 100644
--- a/modules/jooby-test/src/main/java/io/jooby/test/MockRouter.java
+++ b/modules/jooby-test/src/main/java/io/jooby/test/MockRouter.java
@@ -18,6 +18,7 @@
 import io.jooby.Router;
 import io.jooby.SneakyThrows;
 import io.jooby.WebSocket;
+import io.jooby.problem.ProblemDetailsHandler;
 
 /**
  * Utility class that allows us to execute routes using a {@link MockContext}.
@@ -74,6 +75,9 @@ public Object value() {
    * @param application Source application.
    */
   public MockRouter(@NonNull Jooby application) {
+    if (application.problemDetailsIsEnabled()) {
+      application.error(ProblemDetailsHandler.from(application.getConfig()));
+    }
     this.supplier = () -> application;
   }
 
@@ -472,6 +476,8 @@ public void tryError(Throwable cause, Consumer<MockResponse> consumer) {
    */
   public void tryError(Throwable cause, Context ctx) {
     var app = supplier.get();
+    MockContext findContext = ctx instanceof MockContext ? (MockContext) ctx : newContext();
+    findContext.setRouter(app);
     var handler = app.getErrorHandler();
     handler.apply(ctx, cause, app.errorCode(cause));
   }
diff --git a/tests/src/test/java/io/jooby/i3787/Application.java b/tests/src/test/java/io/jooby/i3787/Application.java
new file mode 100644
index 0000000000..af2968dc7c
--- /dev/null
+++ b/tests/src/test/java/io/jooby/i3787/Application.java
@@ -0,0 +1,33 @@
+package io.jooby.i3787;
+
+import com.typesafe.config.Config;
+import com.typesafe.config.ConfigFactory;
+import io.jooby.Jooby;
+import io.jooby.problem.HttpProblem;
+
+import java.util.Map;
+
+class Application extends Jooby {
+  {
+    Config problemDetailsConfig = ConfigFactory.parseMap(
+        Map.of("problem.details.enabled", true)
+    );
+    getEnvironment().setConfig(problemDetailsConfig.withFallback(getConfig()));
+
+    get("/throw", ctx -> {
+      throw new CustomException();
+    });
+
+    error(CustomException.class, (ctx, throwable, statusCode) -> {
+      var problem = HttpProblem.badRequest("A Client Error — Obviously");
+      ctx.getRouter().getErrorHandler().apply(ctx, problem, statusCode);
+    });
+  }
+
+  public static void main(String[] args) {
+    runApp(args, Application::new);
+  }
+
+  static class CustomException extends RuntimeException {
+  }
+}
diff --git a/tests/src/test/java/io/jooby/i3787/Issue3787.java b/tests/src/test/java/io/jooby/i3787/Issue3787.java
new file mode 100644
index 0000000000..4f0f50ad0c
--- /dev/null
+++ b/tests/src/test/java/io/jooby/i3787/Issue3787.java
@@ -0,0 +1,20 @@
+package io.jooby.i3787;
+
+import io.jooby.StatusCode;
+import io.jooby.test.MockContext;
+import io.jooby.test.MockRouter;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class Issue3787 {
+
+  private final MockRouter router = new MockRouter(new Application()).setFullExecution(true);
+
+  @Test
+  void issue3787() {
+    var ctx = new MockContext();
+    router.tryError(new Application.CustomException(), ctx);
+    assertEquals(StatusCode.BAD_REQUEST, ctx.getResponseCode());
+  }
+}