locate: can not open `/var/lib/mlocate/mlocate.db': Permission denied - Solved!

$ locate unicycler
locate: can not open `/var/lib/mlocate/mlocate.db': Permission denied

Changing the permission solved the issue!

$ sudo chmod -R 755 /var/lib/mlocate/mlocate.db

$ locate unicycler
/home/user/Lab_Doc_Share/Assembly/SA3_Noclean_barcode01_unicycler.log