PSQLException: current transaction is aborted, commands ignored until end of transaction block

I got this error using Java and PostgreSQL doing an insert on a table. I will illustrate how you can reproduce this error:

org.postgresql.util.PSQLException: ERROR: 
current transaction is aborted, commands ignored until end of transaction block

Summary:

The reason you get this error is because you have entered a transaction and one of your SQL Queries failed, and you gobbled up that failure and ignored it. But that wasn't enough, THEN you used that same connection, using the SAME TRANSACTION to run another query. The exception gets thrown on the second, correctly formed query because you are using a broken transaction to do additional work. PostgreSQL by default stops you from doing this.

I'm using: PostgreSQL 9.1.6 on x86_64-redhat-linux-gnu, compiled by gcc (GCC) 4.7.2 20120921 (Red Hat 4.7.2-2), 64-bit".

My PostgreSQL driver is: postgresql-9.2-1000.jdbc4.jar

Using Java version: Java 1.7

Here is the table create statement to illustrate the Exception:

CREATE TABLE moobar
(
    myval   INT
);

Java program causes the error:

public void postgresql_insert()
{
    try  
    {
        connection.setAutoCommit(false);  //start of transaction.
        
        Statement statement = connection.createStatement();
        
        System.out.println("start doing statement.execute");
        
        statement.execute(
                "insert into moobar values(" +
                "'this SQL statement fails, and it " +
                "is gobbled up by the catch, okfine'); ");
     
        //The above line throws an exception because we try to cram
        //A string into an Int.  I Expect this, what happens is we gobble 
        //the Exception and ignore it like nothing is wrong.
        //But remember, we are in a TRANSACTION!  so keep reading.

        System.out.println("statement.execute done");
        
        statement.close();
        
    }
    catch (SQLException sqle)
    {
        System.out.println("keep on truckin, keep using " +
                "the last connection because what could go wrong?");
    }
    
    try{
        Statement statement = connection.createStatement();
        
        statement.executeQuery("select * from moobar");

        //This SQL is correctly formed, yet it throws the 
        //'transaction is aborted' SQL Exception, why?  Because:
        //A.  you were in a transaction.
        //B.  You ran a SQL statement that failed.
        //C.  You didn't do a rollback or commit on the affected connection.
        
    }
    catch (SQLException sqle)
    {
        sqle.printStackTrace();
    }   

}

The above code produces this output for me:

start doing statement.execute

keep on truckin, keep using the last connection because what could go wrong?

org.postgresql.util.PSQLException: 
  ERROR: current transaction is aborted, commands ignored until 
  end of transaction block

Workarounds:

You have a few options:

1. Simplest solution: Don't be in a transaction. Set the connection.setAutoCommit(false); to connection.setAutoCommit(true);. It works because then the failed SQL is just ignored as a failed SQL statement. You are welcome to fail SQL statements all you want and PostgreSQL won't stop you.

2. Stay being in a transaction, but when you detect that the first SQL has failed, either rollback/re-start or commit/restart the transaction. Then you can continue failing as many SQL queries on that database connection as you want.

3. Don't catch and ignore the Exception that is thrown when a SQL statement fails. Then the program will stop on the malformed query.

4. Get Oracle instead, Oracle doesn't throw an exception when you fail a query on a connection within a transaction and continue using that connection.

In defense of PostgreSQL's decision to do things this way... Oracle was making you soft in the middle letting you do dumb stuff and overlooking it.

Check the output before the statement that caused current transaction is aborted. This typically means that database threw an exception that your code had ignored and now expecting next queries to return some data.

So you now have a state mismatch between your application, which considers things are fine, and database, that requires you to rollback and re-start your transaction from the beginning.

You should catch all exceptions and rollback transactions in such cases.

Here's a similar issue.