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Looks like "MVC" is some kind of funky Windows thingy, so probably not that strange an IIS webserver is responding.
That said I have absolutely NO idea what MVC is, nor do I have any experience with IIS/Windows based stuff. But even so I would urge @DavidS to explain more about the exact situation of the situation. A lot more.. Because as of now, it's probably just a guessing game for many of us here. "MVC"? "web.config"? Contact the hosting provider to renew the cert? What does this "contact" entail? What does your hosting provider do to actually make it happen? Can't they make that change permanently? If they know something is wrong with your """web.config""", haven't they told you exactly what is wrong with it? Which issue does your hosting provider have with renewal?
This URL /.well-known/acme-challenge/* must be excluded from your site in order for LE to verify the link. (Creating this folder in its directory does not help - it must be excluded in web.config or on the website).
It should be accessible yet I should not have it configured.
I'm not familiar with ACME client to try and renew the cert myself, how can I test this?
I thought only letsencrypt could issue a new cert once the mine expired
All CAs can issue certs.
LetsEncrypt is not the only CA on the Internet.
LetsEncrypt is no longer the only CA that is now offering certs for FREE.
It is however the one with the most community support and experience.
But that test file works perfectly? I can retrieve it in any case. Or is that not suppose to happen? I don't understand..
@rg305 I assume the webhosting provider has an ACME client, otherwise it wouldn't be possible for Loopias to somehow renew it manually.
@DavidS Maybe you could ask Loopias on how to actually "exclude" the path /.well-known/acme-challenge/* in web.config "or on the website"? We just don't have enough information on how the Loopias certificate systems work to help you properly.
Beats me, we don't have enough info for that. I don't know why contacting Loopias would suddenly enable successful renewal. @DavidS hasn't told us the details on the communication between him and Loopias in that regard.