What causes "Error when parsing input schema file: " in apache/beam?

Verify the schema file path/URI is correct and the file exists

apache/beam · error · RuntimeException

Error when parsing input schema file:

Error message

Error when parsing input schema file:

What it means

FileReadSchemaTransformProvider.resolveSchemaStringOrFilePath loads the schema from either the inline schema string or a schema file path via FileSystems. When reading the schema file raises an IOException (file missing, unreadable, network filesystem failure), it is wrapped in a RuntimeException with this message. It means the transform could not obtain the row schema needed to parse input files.

Solutions

Verify the schema file path/URI is correct and the file exists
Check read permissions for the pipeline runner's service account on the file/bucket
Test FileSystems.open with the same URI in a small job or via gsutil/s3 cmd
If the schema is small, inline it in the configuration's schema string instead of a path
Confirm the matching filesystem is registered (gcs-connector/hadoop-fs dependencies)

Example fix

// before
.withSchema("gs://my-bucket/schemas/missing.json")
// after
.withSchema("gs://my-bucket/schemas/user.json") // or inline: "{\"fields\":[...]}"

Defensive patterns

Strategy: validation

Validate before calling

MatchResult res = FileSystems.match(schemaPath);
if (res.metadata().size() != 1)
  throw new IllegalArgumentException("Expected exactly 1 schema file at " + schemaPath
      + ", got " + res.metadata().size());

Try / catch

try {
  apply(FileReadSchemaTransformProvider...);
} catch (RuntimeException e) {
  if (e.getMessage().startsWith("Error when parsing input schema file"))
    LOG.error("Check schema path/permissions: {}", e.getCause());
  throw e;
}

Prevention

Assert the schema file exists with FileSystems.match before running the pipeline
Inline small schemas in the config string to avoid file I/O entirely
Grant the runner service account read access to the schema location

When it happens

Trigger: FileReadSchemaTransformConfiguration with schema set to a file path (e.g. 'gs://bucket/schema.json') where the path doesn't match any file, matches multiple files, or FileSystems.open fails (permission/network error).

Common situations: Wrong GCS/S3/local path; bucket permissions for the pipeline service account; schema file deleted between config authoring and run; ambiguous glob matching more than one file (fails earlier with its own message).

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/d405b576f36941a3. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/io/file-schema-transform/src/main/java/org/apache/beam/sdk/io/fileschematransform/FileReadSchemaTransformProvider.java:222

          return schema;
        }
        checkArgument(
            !result.metadata().isEmpty(),
            "Failed to match any files for the input schema file path.");
        List<ResourceId> resource =
            result.metadata().stream()
                .map(MatchResult.Metadata::resourceId)
                .collect(Collectors.toList());

        checkArgument(
            resource.size() == 1,
            "Expected exactly 1 schema file, but got " + resource.size() + " files.");

        ReadableByteChannel byteChannel = FileSystems.open(resource.get(0));
        Reader reader = Channels.newReader(byteChannel, UTF_8.name());
        return CharStreams.toString(reader);
      } catch (IOException e) {
        throw new RuntimeException("Error when parsing input schema file: ", e);
      }
    }

    private FileReadSchemaTransformFormatProvider getProvider() {
      String format = configuration.getFormat();
      Map<String, FileReadSchemaTransformFormatProvider> providers =
          Providers.loadProviders(FileReadSchemaTransformFormatProvider.class);
      checkArgument(
          providers.containsKey(format),
          String.format(
              "Received unsupported file format: %s. Supported formats are %s",
              format, providers.keySet()));

      Optional<FileReadSchemaTransformFormatProvider> provider =
          Optional.ofNullable(providers.get(format));
      checkState(provider.isPresent());
      return provider.get();
    }

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