spring-projects/spring-boot · error · IllegalStateException

Error reading Docker configuration file '{}'

Error message

Error reading Docker configuration file '{}'

What it means

readPathContent calls Files.readString(path) and wraps any IOException in IllegalStateException. Note the message always says 'Docker configuration file' but readPathContent is shared by both createDockerConfig (config.json) and createDockerContext (meta.json); the path substituted into the message tells you which file failed. Because existence was already checked by the caller, an IOException here almost always means a permission/race/encoding problem rather than a missing file.

Source

Thrown at buildpack/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/docker/configuration/DockerConfigurationMetadata.java:166

	}

	private static String asHash(String currentContext) {
		try {
			MessageDigest digest = MessageDigest.getInstance("SHA-256");
			byte[] hash = digest.digest(currentContext.getBytes(StandardCharsets.UTF_8));
			return HexFormat.of().formatHex(hash);
		}
		catch (NoSuchAlgorithmException ex) {
			throw new IllegalStateException("SHA-256 is not available", ex);
		}
	}

	private static String readPathContent(Path path) {
		try {
			return Files.readString(path);
		}
		catch (IOException ex) {
			throw new IllegalStateException("Error reading Docker configuration file '" + path + "'", ex);
		}
	}

	static final class DockerConfig extends MappedObject {

		private final @Nullable String currentContext;

		private final @Nullable String credsStore;

		private final Map<String, String> credHelpers;

		private final Map<String, Auth> auths;

		private DockerConfig(JsonNode node) {
			super(node, MethodHandles.lookup());
			this.currentContext = valueAt("/currentContext", String.class);
			this.credsStore = valueAt("/credsStore", String.class);
			this.credHelpers = mapAt("/credHelpers", JsonNode::stringValue);

View on GitHub (pinned to 270dfe353f)

Solutions

1. Check and fix permissions: `ls -l <path>` then `chmod +r <path>`.
2. Ensure the path is a regular file, not a directory or special file.
3. If this is a concurrency/race, ensure a single owner of the docker config dir during the build.

// Pre-check readability of the docker config files
Path cfg = resolveConfigPath();
if (Files.exists(cfg) && !Files.isReadable(cfg)) {
    throw new IllegalStateException("Docker config file " + cfg + " is not readable (check permissions).");
}

try {
    build.run();
} catch (IllegalStateException ex) {
    if (ex.getCause() instanceof IOException
            && ex.getMessage().startsWith("Error reading Docker configuration file")) {
        // hint: check file permissions / mount health
    }
    throw ex;
}

When it happens

Trigger: Files.readString(path) at line 163 throws IOException: permission denied, path is a directory, file bytes are not valid UTF-8 and cannot be decoded, or the file was removed between the caller's exists() check and the read.

Common situations: config.json or meta.json chmod 000 or owned by another user; file on a network mount that became inaccessible; antivirus locking the file on Windows; concurrent process deleting the file.

Related errors

• Error parsing Docker configuration file '{}'
• Docker context '{}' does not exist
• Error parsing Docker context metadata file '{}'
• Error creating KeyStore: {}
• File '{}' is not readable

AI-assisted analysis of spring-projects/spring-boot@270dfe353f (2026-08-11). Data as JSON: /api/errors/5ed4faf2b73db714. Report an issue: GitHub.