404 error disappeared when the domain added /index

We are using OJS 3.2 for multiple journals. This morning when visit the journal homepage (eg. www.scientifi.com/index.php/cellresearch), 404 error comes out but there is no problem in other pages. When the journal domain are added /index manually (e.g. www.scientifi.com/index.php/cellresearch/index), it works again. Any solution for that? Thanks.