: Quarkus 3.10.2 Multipart Upload Corrupts Excel Files - "File is Corrupt" Error

[dheebangithup]

Problem:
When uploading .xlsx files via multipart form in Quarkus 3.10.2 (Java 17), the saved files become corrupted. Excel shows "We found a problem with some content" error when opening them. The files are 30-40% larger than the originals, while other file types work fine.

Key Symptoms:

✅ Files appear to upload successfully

❌ Saved .xlsx files are unreadable in Excel

🔍 Hex dumps show altered file signatures

📈 File sizes increase by ~40% (e.g., 100KB → 140KB)

🖼️ Images also affected, but text/PDF files work normally

Environment:

properties
Quarkus: 3.10.2
Java: Amazon Corretto 17
OS: Windows 11 & Linux (both affected)
Storage: Local filesystem (ext4/NTFS)
Current Code:

java

@POST
@Consumes(MediaType.MULTIPART_FORM_DATA)
public Response uploadExcel(@RestForm("file") FileUpload file) throws IOException {
    Path dest = Path.of("uploads", file.fileName());
    
    // DEBUG: Log file sizes
    System.out.printf("Original: %d bytes | Received: %d bytes%n",
        file.size(),
        Files.size(file.uploadedFile()));
    
    Files.copy(file.uploadedFile(), dest, StandardCopyOption.REPLACE_EXISTING);
    
    return Response.ok().build();

```}

import org.jboss.resteasy.reactive.multipart.MultipartFormDataInput;
import org.jboss.resteasy.reactive.PartType;
import jakarta.ws.rs.;
import jakarta.ws.rs.core.MediaType;
import java.io.InputStream;
import java.nio.file.;
import java.util.Map;

@path("/upload")
public class FileUploadResource {

@POST
@Consumes(MediaType.MULTIPART_FORM_DATA)
@Produces(MediaType.TEXT_PLAIN)
public String handleUpload(MultipartFormDataInput input) throws Exception {
    
    // 1. Get the file part
    var filePart = input.getFormData().get("file");
    if (filePart == null) {
        throw new BadRequestException("No file part found");
    }

    // 2. Log file metadata
    String fileName = filePart.getFileName();
    String contentType = filePart.getHeaders().getFirst("Content-Type");
    long size = filePart.getSize();
    System.out.printf(
        "Receiving file: %s (Type: %s, Reported Size: %d bytes)%n",
        fileName, contentType, size
    );

    // 3. Write to local storage with size verification
    Path uploadDir = Paths.get("uploads");
    Files.createDirectories(uploadDir);
    Path target = uploadDir.resolve(fileName);

    try (InputStream is = filePart.getBody()) {
        long bytesCopied = Files.copy(is, target, StandardCopyOption.REPLACE_EXISTING);
        
        // 4. Verify the written file
        long actualSize = Files.size(target);
        System.out.printf(
            "File written: %s (Expected: %d bytes, Actual: %d bytes)%n",
            target, size, actualSize
        );

        if (bytesCopied != actualSize) {
            throw new IOException("File size mismatch after copy");
        }

        return String.format(
            "Successfully saved %s (%d bytes)%n" +
            "Location: %s",
            fileName, actualSize, target.toAbsolutePath()
        );
    }
}

}

Configuration:

properties
quarkus.http.body.handle-file-uploads=true
quarkus.resteasy-reactive.disable-input-stream-buffering=true
quarkus.http.body.uploads.directory=${java.io.tmpdir}
quarkus.http.limits.max-body-size=50MB

[cescoffier]

Can you provide a reproducer?

Does it work with other file format?

[dheebangithup]

This issue occurs only for the XLSX format.

[cescoffier]

I had no problem with that code:

package org.acme;

import jakarta.ws.rs.Consumes;
import jakarta.ws.rs.POST;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;
import org.jboss.resteasy.reactive.server.multipart.MultipartFormDataInput;

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

@jakarta.ws.rs.Path("/upload")
public class FileUploadResource {

    @POST
    @Consumes(MediaType.MULTIPART_FORM_DATA)
    @Produces(MediaType.TEXT_PLAIN)
    public String handleUpload(MultipartFormDataInput input) throws Exception {

        var filePart = input.getValues().get("file").iterator().next();

        String fileName = filePart.getFileName();
        String contentType = filePart.getHeaders().getFirst("Content-Type");
        var size = filePart.getFileItem().getFileSize();
        System.out.printf(
                "Receiving file: %s (Type: %s, Reported Size: %d bytes)%n",
                fileName, contentType, size
        );

        Path uploadDir = Paths.get("uploads");
        Files.createDirectories(uploadDir);
        Path target = uploadDir.resolve(fileName);

        Files.copy(filePart.getFileItem().getFile(), target);

        long actualSize = Files.size(target);
        System.out.printf(
                "File written: %s (Expected: %d bytes, Actual: %d bytes)%n",
                target, size, actualSize
        );

        return String.format(
                "Successfully saved %s (%d bytes)%n" +
                        "Location: %s",
                fileName, actualSize, target.toAbsolutePath()
        );
    }
}

I didn't configure anything.

For very large Excel file (100 Mb+), I just set:

quarkus.http.limits.max-body-size=200m

[cescoffier]

BTW, 3.10 is a bit old, did you try to update to a more recent version?

[dheebangithup]

Thank you @cescoffier , issue resolved