Mysql-EF operation MYSQL sequence does not contain any matching element

The sequence does not contain any matching element. note: an unhandled exception occurs during the execution of the current Web request. Check the stack trace information for details about the error and the source of the error in the code. Exception details: System. invalidOperationException: sequence does not contain any matching element source error: Row 67: using (AllRunSoftContextdbnewAllRunSoftContext () row 68: {row 69: returndb. set (). where (exp ). singleOrD... mysqlnetc # eflinq

The sequence does not contain any matching element.

Note: unprocessed exceptions occur during the execution of the current Web request. Check the stack trace information for details about the error and the source of the error in the code.

Exception details: System. InvalidOperationException: the sequence does not contain any matching element.

SOURCE error:

Row 67: using (AllRunSoftContext db = new AllRunSoftContext ())
Row 68 :{
Row 69: return db. Set (). Where (exp). SingleOrDefault ();
Row 70 :}
Row 71 :}