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 %s.

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.

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)

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.