apache/iceberg · error · UnsupportedOperationException

Cannot modify ManifestEntryWrapper wrapper via set

Error message

Cannot modify ManifestEntryWrapper wrapper via set

What it means

ManifestEntryWrapper in V1Metadata is a read-only StructLike view over a ManifestEntry. Manifest entries are immutable metadata records; set(pos, value) deliberately throws UnsupportedOperationException to prevent in-place corruption of entry data (status, snapshot ids, data file).

Solutions

1. Do not mutate the wrapper; build a new ManifestEntry (e.g. via entry builder) with the desired status/file
2. Copy the wrapped fields into a fresh Record and modify the copy
3. For rewriting entries, use ManifestWriter/ManifestWriter factories rather than mutating existing structs

Example fix

// before
entryWrapper.set(0, Status.DELETED);
// after
ManifestEntry updated = new ManifestEntry(Status.DELETED, entry.snapshotId(), entry.dataSequenceNumber(), entry.fileSequenceNumber(), entry.file());

if (entry instanceof V1Metadata.ManifestEntryWrapper) { throw new IllegalStateException("ManifestEntryWrapper is read-only; build a new ManifestEntry"); }

boolean isReadOnlyEntry(Object s) { return s instanceof V1Metadata.ManifestEntryWrapper || s instanceof V2Metadata.ManifestEntryWrapper; }

try { entryWrapper.set(pos, value); } catch (UnsupportedOperationException e) { throw new IllegalStateException("use ManifestEntry builder instead of mutating entry", e); }

When it happens

Trigger: Calling set(pos, value) on a ManifestEntryWrapper produced by V1Metadata.ManifestEntryWrapper.wrap(entry), e.g. from generic writers or code that mutates entry status/fields in place.

Common situations: Custom manifest writers or rewrite jobs that try to update entry status or data file in place; frameworks that treat all StructLike instances as mutable records.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Cannot modify DataFileWrapper wrapper via set
• Cannot modify ManifestEntryWrapper wrapper via set
• Cannot modify ManifestFileWrapper wrapper via set
• Cannot modify ManifestFileWrapper wrapper via set
• Backup table name cannot be specified

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/678f6a93419cb9c2. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/apache/iceberg/V1Metadata.java:260

    ManifestEntryWrapper() {
      this.size = entrySchema(Types.StructType.of()).columns().size();
      this.fileWrapper = new DataFileWrapper();
    }

    public ManifestEntryWrapper wrap(ManifestEntry<DataFile> entry) {
      this.wrapped = entry;
      return this;
    }

    @Override
    public int size() {
      return size;
    }

    @Override
    public <T> void set(int pos, T value) {
      throw new UnsupportedOperationException("Cannot modify ManifestEntryWrapper wrapper via set");
    }

    @Override
    public <T> T get(int pos, Class<T> javaClass) {
      return javaClass.cast(get(pos));
    }

    private Object get(int pos) {
      switch (pos) {
        case 0:
          return wrapped.status().id();
        case 1:
          return wrapped.snapshotId();
        case 2:
          DataFile file = wrapped.file();
          if (file != null) {
            return fileWrapper.wrap(file);
          }

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