This error stems from the Iceberg table metadata update constraints enforced by the Unity Catalog's REST API. Specifically, the Iceberg REST Catalog currently does not support multiple schema changes in a single commit. Each ALTER TABLE operation that modifies the schema (e.g., adding columns) triggers a SetCurrentSchema update, and the system restricts this to one per commit.

To avoid this error:

• Add columns one at a time using separate ALTER TABLE statements.
• If automating schema evolution, ensure your logic batches column additions sequentially.

columns_comments = {
    "col1": "comment1",
    "col2": "comment2",
    ....
    "col236": "comment236",
}

for col, comment in columns_comments.items():
    spark.sql(f"ALTER TABLE table_name CHANGE COLUMN {col} SET COMMENT '{comment}'")

Consider raising a support ticket or feature request with Databricks if this limitation impacts your workflow significantly.