What causes "source file does not exist or is not a file" in apache/maven?

Ensure the file is fully written and the stream closed before calling put

apache/maven · error · IllegalArgumentException

source file does not exist or is not a file

Error message

source file does not exist or is not a file

What it means

Transport.put(Path source, URI relativeTarget) requires the source to be an existing regular file (Files.isRegularFile). Directories, non-existent paths, and symlinks whose target is missing are rejected with IllegalArgumentException before any network I/O starts, because the underlying PutTask uploads one concrete file.

Source

Thrown at impl/maven-impl/src/main/java/org/apache/maven/impl/DefaultTransport.java:102

            }
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }
    }

    @Override
    public Optional<String> getString(URI relativeSource, Charset charset) {
        requireNonNull(charset, "charset is null");
        Optional<byte[]> data = getBytes(relativeSource);
        return data.map(bytes -> new String(bytes, charset));
    }

    @Override
    public void put(Path source, URI relativeTarget) {
        requireNonNull(source, "source is null");
        requireNonNull(relativeTarget, "relativeTarget is null");
        if (!Files.isRegularFile(source)) {
            throw new IllegalArgumentException("source file does not exist or is not a file");
        }
        if (relativeTarget.isAbsolute()) {
            throw new IllegalArgumentException("Supplied URI is not relative");
        }
        URI target = baseURI.resolve(relativeTarget);
        if (!target.toASCIIString().startsWith(baseURI.toASCIIString())) {
            throw new IllegalArgumentException("Supplied relative URI escapes baseUrl");
        }

        PutTask putTask = new PutTask(target);
        putTask.setDataPath(source);
        try {
            transporter.put(putTask);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

View on GitHub (pinned to e4093d4e12)

Solutions

Ensure the file is fully written and the stream closed before calling put
Guard the call with Files.isRegularFile(source) and fail fast with a clear message
If you meant to publish a directory, package it into a file (jar/zip) first

Example fix

// before: file not created yet
Path jar = buildDir.resolve("app.jar");
transport.put(jar, URI.create("com/acme/app/1.0/app-1.0.jar"));

// after: build, flush, verify, then upload
Files.createDirectories(buildDir);
Files.write(jar, bytes);
if (!Files.isRegularFile(jar)) throw new IllegalStateException("artifact missing: " + jar);
transport.put(jar, URI.create("com/acme/app/1.0/app-1.0.jar"));

Defensive patterns

Strategy: validation

Validate before calling

if (!Files.isRegularFile(source)) {
    throw new IllegalStateException("upload source missing or not a file: " + source);
}
transport.put(source, relativeTarget);

Prevention

Close and flush whatever wrote the file before uploading
In builds, put() only after the artifact-producing step completed
Never pass directories; package directories into jar/zip files first

When it happens

Trigger: Calling put(tempPath, uri) before the file was created; passing a directory Path; passing a Path whose symlink target was deleted; mixing up the two arguments and passing the target directory as source.

Common situations: Deploying an artifact whose JAR has not been built yet due to build-order mistakes; uploading immediately after Files.createTempFile but before writing content plus close; passing the wrong variable (target instead of source).

Related errors

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/7ad0eacf21165f0a. Report an issue: GitHub.