apache/druid · error · UnsupportedOperationException (UOE)

Cannot open character sequence

Error message

Cannot open character sequence

What it means

Unsupported-operation sentinel in S3DataSegmentPuller's FileObject: getCharContent() is rejected since the S3 object is exposed only as a binary stream and cannot be materialized as a character sequence through the FileObject contract.

Solutions

1. Read via openInputStream() and decode characters explicitly if needed.
2. Avoid calling getCharContent() on S3-backed FileObjects.

When it happens

Trigger: Thrown at extensions-core/s3-extensions/src/main/java/org/apache/druid/storage/s3/S3DataSegmentPuller.java:254 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/4fc9869701f57f1f. Report an issue: GitHub.

Appendix: source

Thrown at extensions-core/s3-extensions/src/main/java/org/apache/druid/storage/s3/S3DataSegmentPuller.java:254

        }
      }

      @Override
      public OutputStream openOutputStream()
      {
        throw new UOE("Cannot stream S3 output");
      }

      @Override
      public Reader openReader(boolean ignoreEncodingErrors)
      {
        throw new UOE("Cannot open reader");
      }

      @Override
      public CharSequence getCharContent(boolean ignoreEncodingErrors)
      {
        throw new UOE("Cannot open character sequence");
      }

      @Override
      public Writer openWriter()
      {
        throw new UOE("Cannot open writer");
      }

      @Override
      public long getLastModified()
      {
        if (s3InputStream != null) {
          Instant lastModified = s3InputStream.response().lastModified();
          return lastModified != null ? lastModified.toEpochMilli() : 0L;
        }
        if (objectMetadata == null) {
          objectMetadata = S3Utils.getSingleObjectMetadata(s3Client, coords.getBucket(), coords.getPath());
        }

View on GitHub (pinned to 9b90983fd2)