I got the Schengen visa - Germany in Chennai, but there is error in the photo.
They printed my daughters photo in my sons visa.
My daughters passport is correct.
What is the process to do visa correction?
According to the Handbook for the processing of visa applications:
If an error is detected by the issuing consulate after the visa sticker has been affixed to the travel document, the visa sticker shall be invalidated by drawing a cross with indelible ink on the visa sticker and a new visa sticker shall be affixed to a different page.
Which means you have to apply to the consulate which issued your visa to receive an updated visa sticker with a proper photo.