Errors made during e-filing of income tax returns can cause the return to be declared defective or invalid. Common errors include incorrect or missing details, schedules, and computations, which can delay processing. Another issue is the inability to pay refunds to taxpayers. To ensure trouble-free processing, taxpayers must send the ITR-V acknowledgement to the Centralized Processing Center in Bangalore in a timely manner. They should also correctly provide an email address and mobile number. Filling the latest address, bank account, and IFSC code details accurately is important. Taxpayers should verify tax credits against Form 26AS to avoid mismatches leading to incorrect tax computations.