What causes "Failed trying to process value for key %s." in apache/beam?

Check the chained cause (ex.getCause()) for the real IOException — usually a FileNotFoundException or permission error naming the path

apache/beam · error · RuntimeException

Failed trying to process value for key

Error message

Failed trying to process value for key %s.

What it means

FileAwareFactoryFn.apply() processes config values that reference external files (e.g. secret/file URLs) by rewriting paths, reading referenced files. Each value rewrite is wrapped in an IOException catch that rethrows as a RuntimeException with this message, chaining the original cause. It means reading or processing the external file for one config key failed.

Solutions

Check the chained cause (ex.getCause()) for the real IOException — usually a FileNotFoundException or permission error naming the path
Verify every file-referencing config value points at an existing, readable file accessible from Beam workers
Ensure external files are staged with Beam's --filesToStage or accessible via the filesystem scheme used in the path
Test the path locally by running the same FileAwareFactoryFn processing against the value in a unit test

Example fix

// before
config.put("sasl.ssl.truststore.location", "gs://my-bucket/missing.truststore.jks");
// after
config.put("sasl.ssl.truststore.location", "gs://my-bucket/present.truststore.jks"); // file verified to exist

Defensive patterns

Strategy: try-catch

Validate before calling

java
for (Map.Entry<String,String> e : config.entrySet()) {
  if (e.getValue() != null && e.getValue().contains("://")) {
    // ensure the referenced file exists via Beam FileSystems.match
    FileSystems.match(e.getValue());
  }
}

Try / catch

java
try {
  factoryFn.apply(config);
} catch (RuntimeException ex) {
  if (ex.getMessage().startsWith("Failed trying to process value for key")) {
    log.severe("Config key " + key + " failed: " + ex.getCause());
  }
}

Prevention

Validate all file-referencing config values resolve to readable resources before submitting the pipeline
Always log/report the chained cause, not just the wrapper message
Stage external files explicitly with Beam file staging
Write a unit test running FileAwareFactoryFn against your real config values

When it happens

Trigger: A config value points to a file (e.g. gs:// or local path) whose backing read throws IOException during apply(); e.g. the resolved file does not exist, is unreadable, or the filesystem staging fails while processing that key's value.

Common situations: Kafka bootstrap config with a keystore/truststore path that wasn't staged to the worker; typo in a bucket path; file deleted between config parse and pipeline execution; worker lacks permission on the staged file.

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/6cc7b8113091f668. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/extensions/kafka-factories/src/main/java/org/apache/beam/sdk/extensions/kafka/factories/FileAwareFactoryFn.java:151

                try {
                  String secretId = secretValue.substring(SECRET_VALUE_PREFIX.length());
                  String processedSecret =
                      processSecret(originalValue, secretId, getSecretWithCache(secretId));

                  matcher.appendReplacement(sb, Matcher.quoteReplacement(processedSecret));
                } catch (IllegalArgumentException ia) {
                  throw new IllegalArgumentException("Failed to get secret.", ia);
                }
              } else if (secretFile != null) {
                throw new UnsupportedOperationException("Not yet implemented.");
              }
            }
            matcher.appendTail(sb);
            String processedValue = sb.toString();
            processedConfig.put(key, processedValue);
          }
        } catch (IOException ex) {
          throw new RuntimeException("Failed trying to process value for key " + key + ".", ex);
        }
      }
    } catch (IOException e) {
      throw new RuntimeException("Failed trying to process extra files.", e);
    }

    return createObject(processedConfig);
  }

  /**
   * A function to download files from their specified external storage path and copy them to the
   * provided local filepath. The local filepath is provided by the replacePathWithLocal.
   *
   * @param externalFilePath
   * @param outputFileString
   * @return
   * @throws IOException
   */

View on GitHub (pinned to 12126d8942)