If you can relate to the embarrassing circumstance of wanting to cancel plans without upsetting someone, here are a few strategies for canceling plans without canceling your friendships.

Recognize That the Legitimacy of Any Justification Is Subjective
Everyone will have their own definition of what constitutes a legitimate justification for canceling arrangements. It's essential to remember that you won't satisfy everyone. Generally, individuals are more willing to accept your reasoning if it regards an urgent responsibility or something unexpected. Anticipate that whatever your reason is for canceling, it may not meet their standard of a legitimate justification.
Make a Call
If you need to cancel an arrangement at the last minute, try calling the individual rather than texting. Texting can seem cold and uncaring. On the other hand, a phone call allows the recipient to hear your tone and gauge your sincerity and remorse, making cancellation easier to accept.
Apologize in Advance
Begin with the phrase "I'm sorry," since apologizing communicates that you value the other person's time and energy and are aware of the impact of your cancellation. Recognize your initial commitment and the circumstances behind your cancellation. Perhaps you'll say something along the lines of, 'I understand I committed to attending, but I handled my schedule quite badly. And now I'm faced with a job assignment that I'm certain I won't be able to complete if I don't cancel our plans."
Don't Lie
Even tiny lies may do more harm to a connection than just beginning with the truth. If you must stretch the truth, keep it generic rather than manufacturing a tale by stating something like, "I'm very sorry this is last-minute, but I'm afraid I won't be able to make it." While this remark provides an opportunity for interpretation, it is still preferable to outright lying.
Make a Rescheduling Offer
Once you've explained yourself, attempt to reschedule at a different time. This is one of the most effective methods of canceling without jeopardizing a friendship. This demonstrates that you still value the connection and are willing to devote time and attention to its maintenance.