FxMan

You could just create a text file and name it php.ini and upload it to the folder
if there isn’t one already there.
Make sure it has write permissions.

If your /html/ folder does not have write permissions, I would not change that.

You can also directly edit the php.ini file by ftp without a plugin if you
know what directives you want to change.

I am unable to access my login page.
It just shows “error” on the page.
Nothing else.

I had logged it to check the admin setting in iThemes Security.
to verify that I had changed it to something else.
I made no changes.
I went back a few minutes later and the error showed up.