Requesting SPFile.Exists with other properties gives a FileNotFoundException

Target SharePoint environment

SharePoint Online

What SharePoint development model, framework, SDK or API is this about?

SharePoint CSOM

Developer environment

Windows

What browser(s) / client(s) have you tested

• 💥 Internet Explorer
• 💥 Microsoft Edge
• 💥 Google Chrome
• 💥 FireFox
• 💥 Safari
• mobile (iOS/iPadOS)
• mobile (Android)
• not applicable
• other (enter in the "Additional environment details" area below)

Additional environment details

.NET 6.0
Microsoft.SharePointOnline.CSOM 16.1.26017.12000

Describe the bug / error

This maybe by design, but it caused us a headache to figure this one out.

When we do a CSOM query to know if a file exists, then the the SPFile.Exists property is returned without exceptions. The SPFile.Exists contains a boolean with true or false.

When the Exists CSOM query is executed with more information such as list column names, then the SPFile.Exists contains also true or false without exceptions.

When more file fields are queried at once (to save some extra calls in order and avoid throttling), then an ServerException (FileNotFoundException) is thrown.

Steps to reproduce

Execute the following code fragment:

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

var siteUrl = @"https://....sharepoint.com/subsitent";

// Make sure this file does NOT exists
var fileUrl = $"{siteUrl}/dmsdocs/ThisFileShouldNotExists.txt";

var clientContext = new Microsoft.SharePoint.Client.ClientContext(new Uri(siteUrl));

// Hookup event handler to insert the access token
clientContext.ExecutingWebRequest += (sender, args) =>
{
	args.WebRequestExecutor.RequestHeaders["Authorization"] = $"Bearer {sharePointAccessToken}";
};

var spfile = clientContext.Web.GetFileByUrl(fileUrl);
clientContext.ExecuteQuery();

clientContext.Load(spfile, f => f.Exists);
clientContext.ExecuteQuery();

// spfile.Exists == false

clientContext.Load(spfile, f => f.Exists, f => f.ListItemAllFields.ParentList.Fields.Include(fld => fld.InternalName, fld => fld.FieldTypeKind), f => f.ListItemAllFields);
clientContext.ExecuteQuery();

// spfile.Exists == false

clientContext.Load(spfile, f => f.Exists, f => f.TimeLastModified);
clientContext.ExecuteQuery(); // ISSUE: Throws ServerException (FileNotFoundExeption)

The last ExecuteQuery() call throws a ServerException.

This behavior is unexpected.

Expected behavior

We expected one way or the other, thus either:

• Always throw FileNotFoundException if file does not exists on server
• Always fill Exists with true or false. If file does not exists, then the other properties would raise a PropertyOrFieldNotInitializedException if we try to read these properties. If the file exists, the properties which are fetched should be accessible.