diff --git a/scm-webapp/src/main/java/sonia/scm/api/FallbackExceptionMapper.java b/scm-webapp/src/main/java/sonia/scm/api/FallbackExceptionMapper.java
index feb5341e2d..4815b22bdc 100644
--- a/scm-webapp/src/main/java/sonia/scm/api/FallbackExceptionMapper.java
+++ b/scm-webapp/src/main/java/sonia/scm/api/FallbackExceptionMapper.java
@@ -4,10 +4,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.slf4j.MDC;
 import sonia.scm.api.v2.resources.ErrorDto;
-import sonia.scm.api.v2.resources.ExceptionWithContextToErrorDtoMapper;
 import sonia.scm.web.VndMediaType;
 
-import javax.inject.Inject;
 import javax.ws.rs.core.Response;
 import javax.ws.rs.ext.ExceptionMapper;
 import javax.ws.rs.ext.Provider;
@@ -20,16 +18,9 @@ public class FallbackExceptionMapper implements ExceptionMapper<Exception> {
 
   private static final String ERROR_CODE = "CmR8GCJb31";
 
-  private final ExceptionWithContextToErrorDtoMapper mapper;
-
-  @Inject
-  public FallbackExceptionMapper(ExceptionWithContextToErrorDtoMapper mapper) {
-    this.mapper = mapper;
-  }
-
   @Override
   public Response toResponse(Exception exception) {
-    logger.debug("map {} to status code 500", exception);
+    logger.warn("mapping unexpected {} to status code 500", exception.getClass().getName(), exception);
     ErrorDto errorDto = new ErrorDto();
     errorDto.setMessage("internal server error");
     errorDto.setContext(Collections.emptyList());
diff --git a/scm-webapp/src/main/java/sonia/scm/api/JsonParseExceptionMapper.java b/scm-webapp/src/main/java/sonia/scm/api/JsonParseExceptionMapper.java
new file mode 100644
index 0000000000..dacecb350e
--- /dev/null
+++ b/scm-webapp/src/main/java/sonia/scm/api/JsonParseExceptionMapper.java
@@ -0,0 +1,35 @@
+package sonia.scm.api;
+
+import com.fasterxml.jackson.core.JsonParseException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.slf4j.MDC;
+import sonia.scm.api.v2.resources.ErrorDto;
+import sonia.scm.web.VndMediaType;
+
+import javax.ws.rs.core.Response;
+import javax.ws.rs.ext.ExceptionMapper;
+import javax.ws.rs.ext.Provider;
+import java.util.Collections;
+
+@Provider
+public class JsonParseExceptionMapper implements ExceptionMapper<JsonParseException> {
+
+  private static final Logger logger = LoggerFactory.getLogger(JsonParseExceptionMapper.class);
+
+  private static final String ERROR_CODE = "2VRCrvpL71";
+
+  @Override
+  public Response toResponse(JsonParseException exception) {
+    logger.trace("got illegal json: {}", exception.getMessage());
+    ErrorDto errorDto = new ErrorDto();
+    errorDto.setMessage("illegal json content: " + exception.getMessage());
+    errorDto.setContext(Collections.emptyList());
+    errorDto.setErrorCode(ERROR_CODE);
+    errorDto.setTransactionId(MDC.get("transaction_id"));
+    return Response.status(Response.Status.BAD_REQUEST)
+      .entity(errorDto)
+      .type(VndMediaType.ERROR_TYPE)
+      .build();
+  }
+}