The sign-in name or password does not match one...

Question

I am creating a C# Solution that will migrate the documents from SharePoint 2010 On-Premises to SharePoint Online.

I am done with the program. But when I run the program it runs successfully for few times. After some time it starts throwing error:

Microsoft.SharePoint.Client.IdcrlException: The sign-in name or password does not match one in the Microsoft account system.

I am unable to track the actual error.

Here I am sharing my code:

public void CreateFolderStructures(MigrationFolders migrationFolders)
{
    using (ClientContext clientContext = new ClientContext("Site URL")
    {
        string SPOnlineUsername = "Username";
        string SPOnlinePassword = "PASSWORD";
        foreach (char c in SPOnlinePassword)
        {
            securePassword.AppendChar(c);
        }
        clientContext.Credentials = new SharePointOnlineCredentials(SPOnlineUsername, securePassword);
        var list = clientContext.Web.Lists.GetByTitle(DocumentLibraryName);
        ListItemCreationInformation newItemInfo = new ListItemCreationInformation();
        newItemInfo.UnderlyingObjectType = FileSystemObjectType.Folder;
        newItemInfo.LeafName = migrationFolders.FolderName;
        newItemInfo.FolderUrl = "SITEURL" + migrationFolders.FolderPath;
        ListItem newListItem = list.AddItem(newItemInfo);
        newListItem.Update();
        list.Update();
        clientContext.ExecuteQuery();

        newListItem["Modified"] = migrationFolders.ModifiedDDate;
        newListItem["Created"] = migrationFolders.CreatedDate;
        newListItem.Update();
        list.Update();
        clientContext.ExecuteQuery();
   }
}

The above code is called in foreach loop.

I have gone through following URL but that is not the case with me.

• http://sharepointconnoisseur.blogspot.in/2015/09/how-to-resolve-error.html
• http://kb.cloudiway.com/sharepoint-the-sign-in-name-or-password-does-not-match-one-in-the-microsoft-account-system/
• https://knowledge-junction.com/2017/12/24/office-365-connecting-to-sharepoint-online-site-using-csom-when-multi-factor-authentication-mfa-is-enabled-for-the-user/

Any suggestion how to resolve this error?