why: Internal server error: ORA-40478: output value too large (maximum: 4000) when working with CLOB

[maquejp]

Hello,
I am trying to retrieve a clob from a function in my package, and I received the error ORA-40478.
I am well specifing the output being a CLOB

`
const sql ='
BEGIN
:result := p_accounts.read_accounts(
p_page => :page,
p_page_size => :page_size,
p_sort_by => :sort_by,
p_sort_order => :sort_order,
p_filter => :filter
);
END;
';

const result = await db.executeQuery(sql, {
page: 1,
page_size: 20,
sort_by: 'pk',
sort_order: 'DESC',
filter: '',
result: { dir: oracledb.BIND_OUT, type: oracledb.CLOB },
});
if (result.outBinds && result.outBinds.result) {
// Handle CLOB result - it might be a Lob object that needs to be read
let jsonString: string;
if (typeof result.outBinds.result === 'string') {
jsonString = result.outBinds.result;
} else if (result.outBinds.result && typeof result.outBinds.result.getData === 'function') {
// It's a Lob object, read the data
jsonString = await result.outBinds.result.getData();
} else {
return {
success: false,
message: 'Unexpected response format from database',
data: { resultType: typeof result.outBinds.result },
};
}
// Parse the JSON response from the Oracle package
const jsonResponse = JSON.parse(jsonString);
console.log(jsonResponse);
`

The execute query

`
async executeQuery<T = any>(
sql: string,
binds: any[] | any = [],
options: oracledb.ExecuteOptions = {}
): Promise<oracledb.Result> {
let connection: oracledb.Connection | null = null;

try {
  connection = await this.getConnection();
  
  const defaultOptions: oracledb.ExecuteOptions = {
    outFormat: oracledb.OUT_FORMAT_OBJECT,
    autoCommit: true,
    ...options
  };

  const result = await connection.execute<T>(sql, binds, defaultOptions);
  return result;
} catch (error) {
  console.error('❌ Database query execution failed:', error);
  throw error;
} finally {
  if (connection) {
    try {
      await connection.close();
    } catch (error) {
      console.error('❌ Failed to close database connection:', error);
    }
  }
}

}
}
`

What I have in the console

[0] {
[0] status: 'error',
[0] message: 'Internal server error: ORA-40478: output value too large (maximum: 4000)',
[0] http_status: 500,
[0] data: null,
[0] timestamp: '2025-09-04T09:30:28.607Z'
[0] }

If I reduce the :page to 5 it works

Any idea why? Is it a bug?

[sharadraju]

Hello,
What is the node-oracledb version being used?
What is the Oracle Database version?
If your node-oracledb version is 6.0 or later, are you using Thin or Thick mode?

[maquejp]

I had no time to remove my discussions, it seems that it comes from my package function... Sorry for the inconvenient