Center position of Bootstrap Modal popup in ASP.Net

It is not possible to check at our end. There might be some other css that affecting the modal to display on the right side.

So you need to do inspect element in browser and try to modify the position.

You can check below links.

https://stackoverflow.com/questions/18422223/bootstrap-3-modal-vertical-position-center

https://www.tutorialrepublic.com/faq/how-to-align-bootstrap-modal-vertically-center.php