Good evening, I am self-taught on the subject of java and I am looking for a solution for this exception "Exception in thread" main "java.lang.NoClassDefFoundError: org / aspectj / lang / Signature" which jumps at the moment of trying connect a database with my code in java, I really downloaded the jar of mysql 5.0.8 and nothing, I installed the aspectj from the eclipse software installer and also, I really do not know what to do, since not only it does not let me connect to mysql, nor to ucanaccess, which I have as a second option if mysql presents problems. Thank you in advance.