Add item to SharePoint Online Library - strange Access Denied exception

Question

I have created a very simple SharePoint Online App. It has a manifest and a website. There is a simple script on a Default aspx. It is trying to deploy the file to a Library and getting "Access denied. You do not have permission to perform this action or access this resource." exception when saving to "Style Library", but it saves OK to "SiteAssets".

Here is a code of Default.aspx of my website:

$(document).ready(function () {
        var fileContents = "alert('Hello World');";
        var context = SP.ClientContext.get_current();
        var hostContext = new SP.AppContextSite(context, decodeURIComponent(getQueryStringParameter('SPHostUrl')));
        var web = hostContext.get_web();

        context.load(web);

        var createInfo = new SP.FileCreationInformation();
        createInfo.set_content(new SP.Base64EncodedByteArray());        

        for (var i = 0; i < fileContents.length; i++) {
            createInfo.get_content().append(fileContents.charCodeAt(i));
        }
        createInfo.set_overwrite(true);
        createInfo.set_url("test.js");

        // !!!   magic starts here
        // !!!   Style Library doesn't work (Access Denied)
        // !!!   but SiteAssets does
        var targetFolder = "Style Library";
        // var targetFolder = "SiteAssets";

        var files = hostContext.get_web().getFolderByServerRelativeUrl(targetFolder).get_files();
        files.add(createInfo);

        context.executeQueryAsync(function () {
            alert("Saved successfully");
        }, function (_, args) {
            alert("Well, it's SharePoint. Error message: " + args.get_message());
        });
    });

And here is my paranoid AppPermissionRequests section of AppManifest.xml file:

  <AppPermissionRequests>
    <AppPermissionRequest Scope="http://sharepoint/content/sitecollection" Right="FullControl" />
    <AppPermissionRequest Scope="http://sharepoint/content/tenant" Right="FullControl" />
    <AppPermissionRequest Scope="http://sharepoint/content/sitecollection/web/list" Right="FullControl" />
  </AppPermissionRequests>

I am using SharePoint Hosted model.

So the question is - why the behaviour is different and how can I really set Full Control level of permissions to my App?

Answer 1

Ok, this is an issue with the settings for your tenant. Basically, to test this you can try to upload a document to the Style Library from the UI. You should be getting the same access denied.

How to solve this?

1. Go to the SharePoint administration page for your tenant.
2. Access the Settings page (last item of the left navigation).
3. Locate the section "Custom Script" and make sure both settings are in "Allow users to run custom..."
4. Click OK.

It can take up to 24 hs. to make the changes, but you will be able to upload documents to the Style Library back again.

-Hope it helps