Error System.Text.Json.JsonException

[faurepa]

Hello,
I am new a working with pnpcore. I have downloaded the "pnpcore-dev" sample. I have updated the Client and Tenant ID, and the location that I am trying to access in the appsettings.json file.

Independent of the location (tried two), I keep getting the following error.

System.Text.Json.JsonException
HResult=0x80131500
Message='<' is an invalid start of a value. Path: $ | LineNumber: 1 | BytePositionInLine: 0.
Source=System.Text.Json
StackTrace:
at System.Text.Json.ThrowHelper.ReThrowWithPath(ReadStack& state, JsonReaderException ex)
at System.Text.Json.Serialization.JsonConverter1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state) at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan1 utf8Json, JsonTypeInfo jsonTypeInfo, Nullable1 actualByteCount) at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan1 json, JsonTypeInfo jsonTypeInfo)
at System.Text.Json.JsonSerializer.Deserialize[TValue](String json, JsonSerializerOptions options)
at PnP.Core.Services.JsonMappingHelper.d__1.MoveNext()
at PnP.Core.Services.BatchClient.d__61.MoveNext()
at PnP.Core.Services.BatchClient.d__60.MoveNext()
at PnP.Core.Services.BatchClient.d__37.MoveNext()
at PnP.Core.Model.BaseDataModel`1.d__96.MoveNext()
at PnP.Core.Services.PnPContextFactory.d__56.MoveNext()
at PnP.Core.Services.PnPContextFactory.d__47.MoveNext()
at PnP.Core.Services.PnPContextFactory.d__39.MoveNext()
at PnP.Core.Services.PnPContextFactory.d__36.MoveNext()
at Consumer.Program.

d__0.MoveNext() in C:\Users\H173957\Documents\Code\pnpcore-dev\samples\Demo.Console\Program.cs:line 131
at Consumer.Program.(String[] args)

This exception was originally thrown at this call stack:
[External Code]

Inner Exception 1:
JsonReaderException: '<' is an invalid start of a value. LineNumber: 1 | BytePositionInLine: 0.

I don't know if this is something with the site, or my code.
I am not sure of where to start looking. Any suggestions would be greatly appreciated.
Thank you

[faurepa]

I was wondering if there was a way to see what "using (var context = await pnpContextFactory.CreateAsync("DemoSite"))" line of code (where the failure occurs) is receiving as a webpage. It looking for JSON, but may be getting a webpage. All info line in the command window form the example indicate code 200, which should be good. I had permssions errors (404 and 403), and those were resolved. I jsut can't find what is receiving, or is there a way to change the format of the content that it should receive?

[jansenbe]

@faurepa : that's a weird error. To simplify things, can you first try this minimalistic sample app and see if you've the same issue: https://pnp.github.io/pnpcore/demos/Demo.Console.Minimal/readme.html

[faurepa]

Hello,
I tried the minimal version, and I get an error 403.

info: System.Net.Http.HttpClient.SharePointRestClient.ClientHandler[100]
Sending HTTP request GET https://honeywellprod.sharepoint.com/teams/GlobalPolicyManual/Policies/Forms/AllItems.aspx/_api/Web?$select=Id%2cUrl%2cRegionalSettings%2f*%2cRegionalSettings%2fDateFormat&$expand=RegionalSettings%2cRegionalSettings%2fTimeZone
info: System.Net.Http.HttpClient.SharePointRestClient.ClientHandler[101]
Received HTTP response headers after 177.3786ms - 403
info: System.Net.Http.HttpClient.SharePointRestClient.LogicalHandler[101]
End processing HTTP request after 217.9546ms - 403

Here are the details
PnP.Core.SharePointRestServiceException
HResult=0x80131500
Message=SharePoint Rest service exception
Source=PnP.Core
StackTrace:
at PnP.Core.Services.BatchClient.d__60.MoveNext()
at PnP.Core.Services.BatchClient.d__37.MoveNext()
at PnP.Core.Model.BaseDataModel`1.d__96.MoveNext()
at PnP.Core.Services.PnPContextFactory.d__56.MoveNext()
at PnP.Core.Services.PnPContextFactory.d__47.MoveNext()
at PnP.Core.Services.PnPContextFactory.d__42.MoveNext()
at Program.<

$>d__0.MoveNext() in C:\Users\H173957\Documents\Code\Demo.Console.Minimal\Program.cs:line 38

I noticed that I don't have these delegated permissions granted.
Microsoft Graph -> Sites.Manage.All
SharePoint -> AllSites.Manage

I don't know if I am going to be able to get the Manage All permissions. The software that I am writing is just going to read a file, Will that make a difference to the authentication?
here is a picture of what I have been granted permissions. I have requested for more, but I don't know if I am going to be able to get it.

[faurepa]

I was wondering why Sites.Manage.All and Allsites.Manage are required? If I plan to just reading files. I have no plans or even want to change files.

[jansenbe]

@faurepa : having the SharePoint AllSites.Read and Graph Sites.Read.All should be sufficient. Looking at the error I see "Policies/Forms/AllItems.aspx" in the URL. This makes me think you've specified the site collection wrongly. In your case the site collection to use would be https://honeywellprod.sharepoint.com/teams/GlobalPolicyManual. Can you cross check that?

[faurepa]

Using the Minimal software, I tried to use the path provided, still got the same error message. asked IT to see if there is anything else that might be blocking the software.
I also tried using the demo program (not minimal), and I was able to get past the error message.
I commented out a bunch of code about teams, updating/adding/etc which I don't need, and it seems to be running correctly. So it was just the siteUrl that was causing me an issue.

Now to figure out how to get a list of all the documents in the Policies folder.

[faurepa]

Still odd that "minimal" version doesn't work, but the full version does. I appreciate your help, thank you

[faurepa]

I managed to get a full list of all folders in the root folder using the sample code provided.
Now to get the content of one specific folder. I am essentially enumerating files using the sample code here:
https://pnp.github.io/pnpcore/using-the-sdk/files-intro.html#enumerating-files

await context.Web.LoadAsync(p => p.Folders);

var folder = context.Web.Folders.AsRequested().FirstOrDefault(p => p.Name == "Policies");

// Load files property of the folder
await folder.LoadAsync(p => p.Files);

foreach (var file in folder.Files.AsRequested())
{
    Console.WriteLine($"{file.Title} - Version: {file.Versions}");
}

Program fails on this line: await context.Web.LoadAsync(p => p.Folders);
Here is the console error:
info: System.Net.Http.HttpClient.SharePointRestClient.ClientHandler[100]
Sending HTTP request GET https://honeywellprod.sharepoint.com/teams/GlobalPolicyManual/_api/web?$select=Id%2cFolders&$expand=Folders
info: System.Net.Http.HttpClient.SharePointRestClient.ClientHandler[101]
Received HTTP response headers after 57.426ms - 403
info: System.Net.Http.HttpClient.SharePointRestClient.LogicalHandler[101]
End processing HTTP request after 61.0094ms - 403

Is it possible that I am missing a permission?
Or have I not fully understood how this works?

[faurepa]

OK, thank you to your other support, I have found a solution:

//https://github.com/pnp/pnpcore/discussions/1322
var documentFolder = (await context.Web.Lists.GetByTitleAsync("Policies", p => p.RootFolder));
var allFiles = (await documentFolder.RootFolder.GetAsync(f => f.Files)).Files;

int i = 0;
foreach (var file in allFiles.AsRequested())
{
var extension = Path.GetExtension(file.Name);
Console.WriteLine($"{i} : Filename:{file.Name} - Path: {file.ServerRelativeUrl}");
i++;
}

I appreciate your help.