iPadOS 14.5

In absence of details of the issue or observed errors - assuming your iPad to capable of update - these support pages may be helpful with issues updating your iPad:

Update your iPhone, iPad or iPod touch – Apple Support

If you can't update or restore your iPhone, iPad or iPod touch – Apple Support

If your iPhone, iPad or iPod touch won’t update - Apple Support

If you see an error when you update or restore your iPhone, iPad, or iPod - Apple Support

iOS update and restore errors – Apple Support

Did you see an error? Where you trying to update over the air, or with a computer and iTunes? You will need to provide more information to get a response on how to deal with the issue.