apache/cassandra · error · InvalidRequestException

Altering column types is no longer supported

Error message

Altering column types is no longer supported

What it means

ALTER TABLE ... ALTER columnname TYPE ... (changing a column's type) is no longer supported in modern Cassandra. The AlterTableStatement.TypeChange.apply is a stub that unconditionally throws this InvalidRequestException regardless of input.

Solutions

1. Remove the ALTER TYPE statement; migrate data manually instead: add a new column of the desired type, backfill, then drop the old column
2. Recreate the table with correct types and copy data (e.g. via COPY or a Spark job)
3. Validate client drivers/ORMs do not emit ALTER ... TYPE during upgrades

Example fix

// before
session.execute("ALTER TABLE my_app.events ALTER payload TYPE blob");
// after
session.execute("ALTER TABLE my_app.events ADD payload_v2 blob");
// backfill payload_v2 from payload, then: ALTER TABLE my_app.events DROP payload;

if (alterStmt.trim().toLowerCase().matches("alter table \\S+ alter \\S+ type \\S+"))
    throw new UnsupportedOperationException("Column type changes are unsupported; migrate data manually");

try {
    session.execute(alter);
} catch (InvalidRequestException e) {
    if (e.getMessage().equals("Altering column types is no longer supported"))
        log.error("Rewrite migration: use add-new-column + backfill + drop-old-column");
    else throw e;
}

When it happens

Trigger: Executing 'ALTER TABLE ks.tbl ALTER col TYPE <newtype>' — the legacy type-change syntax; any code path mapped to the TypeChange sub-statement fires this on apply

Common situations: Upgrading from very old Cassandra (0.7/1.x era where type changes were briefly allowed); porting legacy migration scripts; following outdated tutorials or ORM-generated DDL that emits ALTER TYPE.

Understand the failure class

Background: "is deprecated and will be removed" — deprecation warnings for old API names, keywords, and options, and how to migrate before the removal release — this error's family across 29 libraries.

Related errors

• ACCESS TO DATACENTERS operations not supported by…
• Cannot add a counter column to Accord table
• Cannot add new column to a COMPACT STORAGE table
• Cannot drop a table when materialized views still depend on…
• Cannot use ALTER TABLE on a materialized view; use ALTER…

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/44ac7f05eec444d2. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/cql3/statements/schema/AlterTableStatement.java:180

    }

    abstract KeyspaceMetadata apply(Epoch epoch, KeyspaceMetadata keyspace, TableMetadata table, ClusterMetadata metadata);

    /**
     * {@code ALTER TABLE [IF EXISTS] <table> ALTER <column> TYPE <newtype>;}
     *
     * No longer supported.
     */
    public static class AlterColumn extends AlterTableStatement
    {
        AlterColumn(String keyspaceName, String tableName, boolean ifTableExists)
        {
            super(keyspaceName, tableName, ifTableExists);
        }

        public KeyspaceMetadata apply(Epoch epoch, KeyspaceMetadata keyspace, TableMetadata table, ClusterMetadata metadata)
        {
            throw ire("Altering column types is no longer supported");
        }

        @Override
        public boolean compatibleWith(ClusterMetadata metadata)
        {
            return metadata.directory.commonSerializationVersion.isAtLeast(Version.V0);
        }
    }

    /**
     * {@code ALTER TABLE [IF EXISTS] <table> ALTER [IF EXISTS] <column> ( MASKED WITH <newMask> | DROP MASKED )}
     */
    public static class MaskColumn extends AlterTableStatement
    {
        private final ColumnIdentifier columnName;
        @Nullable
        private final ColumnMask.Raw rawMask;
        private final boolean ifColumnExists;

View on GitHub (pinned to 88fd0f6a0e)