There's a reasonable chance your ISP does NOT support SQL Server Express Edition. 9 out of 10 times, you have on-line tools to manage your database, or you need to send them a .bak or .mdf file which they will restore or attach for you.
As I said before and wrote in my article, you most likely need an attached
copy of the database on the server. You can't just upload the MDF file in App_Data and expect it to work. While this works fine in a development scenario, this is typically not how ISPs operate.
There's also a fair chance your ISP has FAQs about this, detailing the steps you need to take to make this work.
Now, of course you can keep trying for ever to get AttachDbFilename to work on your remote machine, but if you want to make this work as soon as possible, you need to look at other resources and means to do this, as suggested in this thread.
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