A FormatFlagsConversionMismatchException is an unchecked runtime exception which is thrown when a conversion and a flag are incompatible in the source code. This is a very common exception encountered when the programmer tries to format the string. Unless otherwise specified, passing a null argument to any method or constructor in this class will cause a NullPointerException to be thrown.

A ServiceConfigurationError is thrown in Java when a service provider cannot be loaded successfully. For instance, the format of the provider-configuration file appears to violate some aspect of the specification.

The NoCredentialsError is an error encountered when using the Boto3 library to interface with Amazon Web Services (AWS). Specifically, this error is encountered when your AWS credentials are missing, invalid, or cannot be located by your Python script. These credentials are stored by default at ~/.aws/credentials which contains your access key and secret access key for using AWS services, along with other configuration details such as your region code.

OperationalError is a class of error encountered while working with the psycopg library in Python. Operational errors are closely linked with the connect method within psycopg and typically occur when parameters passed to this method are incorrect or invalid. This may mean that a parameter, such as a database name, is spelled incorrectly, has changed, or that the database server itself is experiencing a problem.

The JavaScript RangeError: Maximum call stack size exceeded is an error that occurs when there are too many function calls, or if a function is missing a base case.

The psycopg2.errors.UniqueViolation is an error thrown by the when a user attempts to insert a duplicate key value. In an SQL or SQL-like database a key value is defined when a table is created. This key value is then used to reference specific rows of the table. In order to make calls to these rows unambiguous, this key value must be unique for every row. Any attempt to insert a new row which has a value in the key field that already exists in the table cannot be completed.

The Javascript ReferenceError occurs when referencing a variable that does not exist or has not yet been initialized in the current scope. The ReferenceError: event is not defined usually occurs while using an event handler if the event parameter is either not declared or declared incorrectly. For example, if on an onclick event, the handler does not declare the event parameter, this error is thrown.