Vaadin Upload Broken In 23.6.5: A Critical Fix Needed

by Admin 54 views
Vaadin Upload Regression Causing Fatal `NoSuchFieldError` in 23.6.5: A Deep Dive

Hey guys! Let's talk about a pretty gnarly bug that's popped up in Vaadin 23.6.5, specifically with the Upload component. If you're using this version, you might be pulling your hair out because file uploads are probably failing spectacularly. This is a big deal, and we're going to break down what's happening, why it's happening, and what you can do about it. This affects all users in production and developer mode.

The Bug: Upload Component Woes

So, what's the deal? The core issue is a java.lang.NoSuchFieldError: INSTANCE error that's thrown when you try to upload a file using the Vaadin Upload component (com.vaadin.flow.component.upload.Upload) in Vaadin 23.6.5 and later versions. This error originates from Apache Commons FileUpload. The super frustrating thing? The exact same code works perfectly fine in Vaadin 23.6.0. This regression, introduced in a minor update, completely breaks a critical feature – file uploads. This isn't just an inconvenience; it's a showstopper for any application that relies on users being able to upload files. This is something that could have been prevented with better integration testing with its transitive dependencies.

Impact on Your App

  • Uploads are Dead: Any attempt to upload a file results in a server-side error. This means users can't upload documents, images, or anything else they need to. The error is so severe that, once triggered, it can cause subsequent requests to fail until you restart the server. Your application grinds to a halt for file uploading capabilities.

  • Reliability Issues: The error happens inside Vaadin's StreamReceiverHandler, a core part of the framework. This means it's not just a specific feature that's broken; it's a fundamental process that's failing, which can impact the entire application. The critical failures increase dramatically.

  • Quality Concerns: Minor version updates are supposed to improve things, not break them. The fact that a minor update (23.6.5) introduced a regression of this magnitude is a significant concern for anyone relying on the stability of Vaadin. The system's confidence in updates is severely undermined.

Timeline of the Issue: When Did Things Go Wrong?

Let's be clear about when this started causing problems:

  • Works Perfectly: Vaadin 23.6.0 – The Upload component behaves as expected. No errors, no drama. Your users can upload files without a hitch. Everything is as it should be.
  • Broken Badly: Vaadin 23.6.5 and later – The Upload component throws the NoSuchFieldError on the first upload attempt. Subsequent requests also fail. The regression is clear and present within the 23.6 minor line.

This straightforward timeline highlights the severity of the regression. It's a clear indication that something went seriously wrong between these versions.

What's Actually Happening: The Technical Breakdown

Okay, let's dive into the nitty-gritty. What's the error, and where is it coming from?

  • The Culprit: The server throws java.lang.NoSuchFieldError: INSTANCE inside Apache Commons FileUpload when Vaadin’s StreamReceiverHandler tries to process the multipart stream. This is a very specific type of error.
  • The Propagation: The error ripples through the system. It starts in the StreamReceiverHandler.handleMultipartFileUploadFromInputStream method, which causes Servlet.service() to fail. This is a core part of how the server processes requests.
  • The Aftermath: Once the initial error occurs, every subsequent upload request will fail until you restart the application. This is because the error corrupts the system's ability to handle file uploads.

Logs and Stack Trace: The Evidence

Here’s a snippet of the stack trace. It points directly to the problem:

java.lang.NoSuchFieldError: INSTANCE at org.apache.commons.fileupload.util.Streams.copy(Streams.java:151) ~[commons-fileupload-1.6.0.jar!/:1.6.0] at org.apache.commons.fileupload.util.Streams.copy(Streams.java:127) ~[commons-fileupload-1.6.0.jar!/:1.6.0] at org.apache.commons.fileupload.MultipartStream.readBodyData(MultipartStream.java:834) ~[commons-fileupload-1.6.0.jar!/:1.6.0] ... at com.vaadin.flow.server.communication.StreamReceiverHandler.handleMultipartFileUploadFromInputStream(StreamReceiverHandler.java:260) ~[flow-server-23.6.7.jar!/:23.6.7] .

As you can see, the error occurs within the Apache Commons FileUpload library, specifically in the Streams.copy method. This is where the incompatibility lies.

What's Causing the Problem? The Suspected Root Cause

Let's get to the bottom of this. Why is this happening? The likely culprit is a mismatch in dependencies.

  • Dependency Incompatibility: The NoSuchFieldError: INSTANCE usually means there's a problem with the versions of the Apache Commons FileUpload library and its supporting libraries, specifically Apache Commons IO. These libraries must be compatible to work correctly.
  • The Vaadin Connection: In Vaadin 23.6.0, the dependency versions are correctly aligned, and uploads work as expected. In 23.6.5+, it appears that Vaadin has updated to commons-fileupload-1.6.0 without ensuring the corresponding version of Commons IO is also compatible. This mismatch causes the linkage error at runtime.
  • The Vaadin Layer: The failure happens within Vaadin's StreamReceiverHandler, which uses Apache Commons FileUpload. Your application code doesn't directly call these libraries, so the problem is with how Vaadin is managing its dependencies.

In simple terms: A minor Vaadin update introduced a broken version of Apache Commons FileUpload, which breaks file uploads. This is exactly the kind of issue that a stable release should not introduce.

Workarounds? Did We Try Anything?

Here’s what we've tried to get around this:

  • Reverting to a Working Version: Pinning Vaadin back to 23.6.0 immediately fixes the upload functionality. This confirms that the problem is specific to the newer versions.
  • No Code Changes: We tested the same application code and the same runtime environment. The only change was the Vaadin version.
  • No Easy Fix: We haven’t found a workaround within the 23.6.5+ versions, because the error occurs inside Vaadin's server communication layer before your application code can even start processing the data.

What We Need: The Call for Action

Vaadin, we need your help! Here’s what we’re requesting:

  • Acknowledge and Fix the Issue: Please confirm the dependency mismatch causing the NoSuchFieldError in the Upload component.
  • Provide a Patch: Release a patched version of 23.6.x where uploads work correctly (like in 23.6.0). This should involve ensuring compatible versions of Apache Commons FileUpload and its supporting libraries.
  • Transparency: Share the exact dependency changes and verification steps so that development teams can audit the transitive dependencies and avoid these hidden runtime errors in the future.
  • Strengthen Testing: Improve integration tests around multipart uploads to prevent similar regressions in future minor updates.

Expected Behavior: What Should Happen?

  • Successful Uploads: The Upload component should parse multipart/form-data correctly and deliver the file to the registered receiver/buffer without any server-side errors.
  • Stable Updates: Minor updates within a stable line (like the 23.6 series) should never introduce breaking changes to a core component like Upload.

How to Reproduce: Steps to Make it Fail

Want to see this happen yourself? Here’s how:

  1. Set Up Your App: Start a Vaadin Spring Boot application using 23.6.5+ that includes a basic Upload component. For example:
    • View: A page with new Upload() connected to a memory buffer or a receiver listener.
    • No custom servlet filters or special handling is required.
  2. Open the App: Access the application and navigate to the view containing the Upload component.
  3. Try to Upload: Upload any file (a small text file or an image will do).
  4. Watch it Fail: Observe the server-side error and the broken upload behavior.

System Info: The Environment Details

Here's the technical information about the environment where the bug was observed:

  • Vaadin: Flow 23.6.5 (but working in 23.6.0)
  • Spring Boot: 2.7.18
  • Servlet Container: Tomcat 9.0.83 (embedded)
  • Java: OpenJDK 11.0.4 (Alpine)
  • Key Dependencies: flow-server-23.6.5.jar, vaadin-spring-23.6.5.jar
  • Mode: Production and Developer

It is important to note that the latest extended maintenance version is 23.6.5, published on Nov 20, 2025 as described in the maintained older release.

This is a critical issue that needs attention. Let's get this fixed so we can keep building awesome Vaadin applications!