Installing Theme hits 404 Page.

Weird. My previous reply disappeared. Sorry if this is going to cause a double post.

I was hoping that would not be your answer. That’s the URL that should be seen when installing or updating a theme, so there isn’t an issue of something sending off the request somewhere strange.

What remains is that something blocking the request. There are many things that this could be:

1) Your host’s network or server firewall (they sometimes see things like the word “upload”, get scared, and block the request).
2) A plugin, such as a security or caching plugin.
3) Web server or PHP configuration that blocks file uploads above a certain size.
4) Something else that I can’t think of.

The really odd thing is that most security blocks result in a 403 Forbidden error and that blocking requests that are too large should result in a 413 Payload Too Large error. Can you confirm that it was a 404 error and not some other kind of error?

It’s also possible that whatever is blocking access to that page intentionally is sending the wrong error code.

I know that this information isn’t very helpful, but unfortunately, I don’t have much to work with. Have you tried contacting your host about this issue? They might know the cause and have a solution. I recommend giving them the URL at issue and any other relevant details.

Best of luck Paul. Sometimes it can be difficult to get to the root of the issue since there are so many potential sources of the issue. If possible, could you provide the following:

Can you confirm that you are getting a 404 Not Found error rather than something similar such as a 403 error?

Can you provide a list of active plugins?