Updated requirement info around PFX files

There is no apparent info on the serial and cipher requirements to uploaded PFX files and OpenSSL v3 has changed both to more secure versions, but those are not supported when uploading to axure and the error just syas the password is wrong or the certificat is invalid.

Author: MichaelFrandsenMVP

articles/app-service/configure-ssl-certificate.md

@@ -286,6 +286,11 @@ Export your merged TLS/SSL certificate with the private key that your certificat
 
 If you generated your certificate request using OpenSSL, then you have created a private key file. To export your certificate to PFX, run the following command. Replace the placeholders _<private-key-file>_ and _<merged-certificate-file>_ with the paths to your private key and your merged certificate file.
 
+> [!NOTE]
+> OpenSSL v3 creates certificate serials with 20 octets (40 chars) as the X.509 specification allows. Currently only 10 octets (20 chars) is supportet when uploading certificate PFX files.
+> OpenSSL v3 also changed default cipher from 3DES to AES256, but this can be overridden on the command line.
+> OpenSSL v1 uses 3DES as default and only uses 8 octets (16 chars) in the serial, so the PFX files generated are supported without any special modifications.
+
 ```bash
 openssl pkcs12 -export -out myserver.pfx -inkey <private-key-file> -in <merged-certificate-file>  
 ```