I got exception when I try to update webpart programmatically, it says I need to check out the page

Question

I have a custom webpart. Inside this webpart there is some logic to update the webpart settings. See below the code.

I edit the page where the webpart is located. I click on a button which will update the webpart and run the code below.

It gives me an exception like:

WebPartPageUserException: The file is not checked out. You must first check out this document before making changes.

Why do I got this exception? I checked this page out.

private bool SetWebPartProperties(string pageUrl, string webPartId)
        {
            Microsoft.SharePoint.Utilities.SPUtility.ValidateFormDigest();
            SPWeb currentWeb = SPContext.Current.Web;

            PublishingWeb publishingWeb = null;
            PublishingPage page = null;

            SPSecurity.RunWithElevatedPrivileges(
                delegate()
                {
                    using (SPSite site = new SPSite(currentWeb.Url))
                    {
                        using (SPWeb web = site.OpenWeb())
                        {
                            if (PublishingWeb.IsPublishingWeb(web))
                            {
                                publishingWeb = PublishingWeb.GetPublishingWeb(web);
                                PublishingPageCollection pages = publishingWeb.GetPublishingPages();

                                if (pages[pageUrl] != null)
                                {
                                    page = pages[pageUrl];
                                    if (page.ListItem.File.CheckOutType == SPFile.SPCheckOutType.None)
                                    {
                                        page.CheckOut();
                                    }
                                }
                            }

                            SPLimitedWebPartManager wpm = null;

                            // Here you will use the url of the page to get an instance of its
                            // WebPartManager - with this object, you will be able to find and
                            // update your web part....
                            wpm = web.GetLimitedWebPartManager(pageUrl, PersonalizationScope.Shared);

                            // ... using its id to find it in the WebParts collection of the
                            // WebPartManager.
                            System.Web.UI.WebControls.WebParts.WebPart wp = wpm.WebParts[webPartId];

                            // ... and this setting is important, otherwise it won't accept
                            // changes by code. Notice that I'm setting it back to false after
                            // the update...
                            wpm.Web.AllowUnsafeUpdates = true;

                            // DO SOME LOGIC


                            // ... and then you save it...
                            wpm.SaveChanges(wp); // HERE THE ERROR OCCURED
                            wpm.Web.AllowUnsafeUpdates = false;

                            wpm.Dispose();

                            string checkinComment = string.Format("Hoofditems: {0} Aantal nieuwsitems: {1}", "", maxDays);
                            page.CheckIn(checkinComment);
                            SPFile pageFile = page.ListItem.File;
                            pageFile.Publish(checkinComment);
                        }
                    }
                });

            return true;
        }

Answer 1

The problem may be that you use an elevated section, meaning the code runs under the identity of System. However, the page is being edited by (and checked-out to) the current user, the one who clicked the button.

Thus, the error probably means the code cannot edit a file checked-out by someone else (and you never reach you page.CheckOut()call by the way).

Why do you need that elevation of privileges? As the current user has entered edit mode, he has the permissions to edit the Web part... so you may use the contextual SPWeb directly (SPContext.Current.Web).