Merge pull request MicrosoftDocs#1521 from bspender/patch-1

Doc changes to make modern authentication easier

Author: kenwith

sharepoint/sharepoint-ps/sharepoint-pnp/Connect-PnPOnline.md

@@ -3,6 +3,7 @@ external help file:
 applicable: SharePoint Server 2013, SharePoint Server 2016, SharePoint Online
 schema: 2.0.0
 ---
+
 # Connect-PnPOnline
 
 ## SYNOPSIS
@@ -60,7 +61,7 @@ Connect-PnPOnline -Scopes <String[]>
                   [-NoTelemetry [<SwitchParameter>]]
 ```
 
-### WebLogin
+### WebLogin 
 ```powershell
 Connect-PnPOnline -Url <String>
                   -UseWebLogin [<SwitchParameter>]
@@ -241,6 +242,12 @@ Connect-PnPOnline -Url <String>
 ## DESCRIPTION
 If no credentials have been specified, and the CurrentCredentials parameter has not been specified, you will be prompted for credentials.
 
+*For SharePoint Online*: If legacy authentication protocols have been disabled (i.e. When `powershell(Get-PnPTenant).LegacyAuthProtocolsEnabled` returns False), the connection attempt will fail with a message such as the following when using a generic credential object (such as that created by `powershellGet-Credential`) or when using the default options, which prompts for a username and password within the shell:
+
+>Failed to connect to (site), Exception calling "ExecuteQuery" with "0" argument(s): "Cannot contact web site (site) or the web site does not support SharePoint Online credentials. The response status code is 'Unauthorized'. The response headers are 'X-SharePointHealthScore=0, X-MSDAVEXT_Error=917656; Access+denied.+Before+opening+files+in+this+location%2c+you+must+first+browse+to+the+web+site+and+select+the+option+to+login+automatically.
+
+Instead, ensure that you specify the appropriate options that support modern authentication, such as connections with the "-UseWebLogin" or "-PnPO365ManagementShell" parameters or certificate based authentication.
+
 ## EXAMPLES
 
 ### ------------------EXAMPLE 1------------------
@@ -920,4 +927,4 @@ Accept pipeline input: False
 
 ## RELATED LINKS
 
-[SharePoint Developer Patterns and Practices](http://aka.ms/sppnp)
+[SharePoint Developer Patterns and Practices](http://aka.ms/sppnp)