1. First, identify the root cause of the PostgreSQL 42P16 error. This error is caused by a syntax error in the SQL statement. To identify the exact syntax error, use the following code snippet to view the statement that caused the error:

SELECT * FROM pg_stat_activity WHERE state = '42P16'

2. Once the statement causing the error is identified, use the following code snippet to view the syntax of the statement:

\s 

3. After identifying the syntax error, use the following code snippet to fix the syntax error:

ALTER  SET syntax = 'correct syntax'

4. After fixing the syntax error, use the following code snippet to check if the error is resolved:

SELECT * FROM pg_stat_activity WHERE state = '42P16'

5. If the error is still present, use the following code snippet to view the log file for more information:

SELECT * FROM pg_logfile_lines WHERE state = '42P16'

6. After identifying the root cause of the error, use the following code snippet to fix the issue:

ALTER  SET syntax = 'correct syntax'

7. Finally, to ensure that the PostgreSQL 42P16 error does not occur again, it is recommended to use an automated database observability tool. This tool can assist in monitoring and fixing the PostgreSQL 42P16 in question by providing real-time insights into the database performance and alerting the user when an issue arises. This can help to quickly identify and fix any issues before they become a major problem.