It's likely not a major issue, but it's best to clarify with the admitting authority as soon as possible

Filling date of birth instead of exam passing out year might seem like a big mistake, but it's a relatively simple error to rectify. The good news is you caught it during the document upload process. This allows you to address it before the application deadline.

Locate the contact details (email or phone number) for the admissions office or student support department of the institution you are applying to. You can usually find this information on their website. Briefly explain that you mistakenly entered your date of birth instead of the exam passing out year during document upload. Ask how you can correct the error. They might ask you to re-upload the document with the correct information or provide them with the passing out year through email.

In most cases, admitting authorities understand such minor mistakes during the application process. Being proactive and reaching out to them demonstrates your attentiveness and should allow for a smooth correction.

I hope it helps!