Updating Aadhaar in EPF UAN Portal
As you see in the below screenshot my Aadhaar has not been updated in the UAN Portal.To update Aadhaar follow the below steps

Steps to Update Aadhaar
Step 1: Go to Manage —> Modify Basic details

Step 2: Modify Basic details would be displayed as shown below, Enter your Aadhaar No, Date of Birth and then click on Update

Step 3: Once you clicked on Update , it will display a popup as shown, Click on Yes in the Popup

Step 4: Changes requested successfully message would be displayed at the top as shown below

Step 5: You have to contact your Employer to approve Aadhaar, once your Employer approves Aadhaar, PF Office will take somewhere between 0-15 working days to approve your Aadhaar