Let’s Encrypt SSL certificate can not be issued for Plesk domains with the 404 error: The filename, directory name, or volume label syntax is incorrect

Symptoms

• A Let's Encrypt certificate can not be issued for all domains in Plesk with:

  Error: Error: Could not issue a Let's Encrypt SSL/TLS certificate for example.com.
  The authorization token is not available at http://example.com/.well-known/acme-challenge/.
  To resolve the issue, make it is possible to download the token file via the above URL.
  See the related Knowledge Base article for details.
  Additional error details:
  Invalid response from https://acme-v01.api.letsencrypt.org/acme/authz/_oRgI1kwh53Fr07VRtI-55Zj7NqY75KI5e41PCsQqow.
  Details:
  Type: urn:acme:error:unauthorized
  Status: 403
  Detail: Invalid response from http://example.com/.well-known/acme-challenge/uxIoK_7-BjsuBu362yQ_QD5ovykddVeyKEgfEAre9P8: "
  HTTP Error 404.0 - Not Found
  The resource you are looking for has been removed, had its name changed, or is temporarily unavailable

• Accessing http://example.com/.well-known/acme-challenge/uxIoK_7-BjsuBu362yQ_QD5ovykddVeyKEgfEAre9P8 in a browser fails with 404.4 error.

Cause

The ApplicationRequestRouting module is not enabled/installed or it's corrupted at Internet Information Services (IIS) Manager > server_hostname > Modules.

The following output is provided when accessing the link from the error message with enabled Failed Request Tracing:

ModuleName IIS Web Core
Notification MAP_REQUEST_HANDLER
HttpStatus 404
HttpReason Not Found
HttpSubStatus 4
ErrorCode The filename, directory name, or volume label syntax is incorrect.

Resolution

1. Connect to the server via RDP.

2. Download and install Application Request Routing package from Microsoft website:

   • Microsoft Application Request Routing 3.0 (x64).

   • Microsoft Application Request Routing 3.0 (x86).

3. Reboot the server after the installation is completed.