Certbot challenge error 404 in webroot mode

This web site runs under Apache on Windows. I installed Windows certbot client and ran it as suggested on its homepage, in webroot mode, since the web site cannot be stopped. This is what it reported:

C:\WWW\somedomain>certbot certonly --webroot Saving debug log to C:\Certbot\log\letsencrypt.log Plugins selected: Authenticator webroot, Installer None Please enter in your domain name(s) (comma and/or space separated)  (Enter 'c' to cancel): somedomain.com Obtaining a new certificate Performing the following challenges: http-01 challenge for somedomain.com Input the webroot for somedomain.com: (Enter 'c' to cancel): c:\www\somedomain Waiting for verification... ←[31mChallenge failed for domain somedomain.com←[0m http-01 challenge for somedomain.com Cleaning up challenges ←[31mSome challenges have failed.←[0m ←[1m IMPORTANT NOTES: ←[0m - The following errors were reported by the server:     Domain: somedomain.com    Type:   unauthorized    Detail: Invalid response from    http://somedomain.com/.well-known/acme-challenge/UIWHcmUsNd_4itYD5IWMLSuldIF4yzd2m9mpSH4W7a0    [2**.1**.1**.2**]: "<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML    2.0//EN\">\n<html><head>\n<title>404 Not    Found</title>\n</head><body>\n<h1>Not Found</h1>\n<p"     To fix these errors, please make sure that your domain name was    entered correctly and the DNS A/AAAA record(s) for that domain    contain(s) the right IP address. 

The certbot server does query the right IP address, so the DNS record is working fine. I suspect that it may not be creating the challenge folder/file. I tried creating the above URL manually and querying it in a browser from elsewhere, and it is being served fine. Any ideas what is missing for certbot? Keep in mind that somedomain.com is only used here for example.