The sharepoint often displays error 429 (Too many requests) and we have already taken all the actions described in the article below, but some requests continue to be blocked.
https://docs.microsoft.com/en-us/sharepoint/dev/general-development/how-to-avoid-getting-throttled-or-blocked-in-sharepoint-online
Our scenario involves a customized desktop application (add-in) for Word, Excel, Power Point and Outlook that accesses the Sharepoint through CSOM (with user's network credentials) and we already registered this Add-in through the "/_layouts/15/AppRegNew.aspx" page and decorated all of our requests with "NONISV|{OUR ORGANIZATION NAME}|{OUR ADDIN NAME}/1.0 ", as described in:
https://docs.microsoft.com/en-us/sharepoint/dev/sp-add-ins/register-sharepoint-add-ins
Follow the instructions in this Microsoft article:
https://docs.microsoft.com/en-us/sharepoint/dev/sp-add-ins/register-sharepoint-add-ins
When you have your Add-In registered, do this when you are creating SharePoint Context (using CSOM):
private void Initialize()
{
this.SPCurrentContext = new ClientContext(this.Url);
if (string.IsNullOrWhiteSpace(this.Domain))
{
this.SPCurrentContext.Credentials = new SharePointOnlineCredentials(this.User, ParseToSecureString(this.Password));
}
else
{
this.SPCurrentContext.Credentials = new NetworkCredential(this.User, ParseToSecureString(this.Password), this.Domain);
}
this.RetryCount = Properties.Settings.Default.DefaultRetryCount;
this.RetryDelay = Properties.Settings.Default.DefaultRetryDelay;
this.NONISV = Properties.Settings.Default.ClientAppNONISV;
this.SPCurrentContext.ExecutingWebRequest += delegate (object sender, WebRequestEventArgs e)
{
e.WebRequestExecutor.WebRequest.UserAgent = this.NONISV; // This is the TRICK!!!
};
}
The NONISV used as User-Agent HTTP Header should be something like:
NONISV|{Your Company Name}|{Your Add-In Name}/1.0
As described here. Good luck!
