There are multiple ways to deal with this if your Canada PR application is rejected. You can request a refusal letter from the concerned authority citing reasons for rejection. If there are no issues in the documentation on reviewing the refusal letter, you can seek clarification with IRCC and appeal to revoke the rejection. In case of errors, you can re-apply with corrected information that addresses the reasons for the previous refusal. If your application was rejected due to eligibility factors, you can try other PR pathways that may suit you. The reasons for denial may be incomplete documentation, criminal history, failure to meet eligibility requirements, prolonged health issues, etc.