SharePoint 2010 "unhandled win32 exception occurred in W3WP.EXE"

Question

I am getting an win32 exception that I need help debugging. I have a SharePoint page that has a custom Web Part that when I browse to that page, I get the following message:

In w3wp.dmp the assembly instruction at ntdll!RtlReportCriticalFailure+62 in 
C:\Windows\System32\ntdll.dll from Microsoft Corporation has caused an unknown
exception (0xc0000374) on thread 43

Unhandled exception at 0xHEX in w3wp.exe: 0xc0000374: 
A heap has been corrupted

I don't really know where to begin debugging this issue and searching the internet has yielded very little results.

I have saved the DMP file and I've loaded it into the Debug Diagnostic Tool for analysis. I don't know what parts are most important, so if someone could tell me which sections I should post, I will post them.

Where I think the problem is:

I have narrowed down the location of where the problem might be. If I don't call these methods, I don't get the error. Is there something wrong with the way I'm accessing the TermStore?

    private void GetTerms()
    {
        using (SPSite site = new SPSite(PhaseListUrl.Value))
        {
            var session = new TaxonomySession(site);
            if (session.TermStores == null || session.TermStores.Count == 0) return;

            OfficeDropdown.Items.Clear();
            OfficeDropdown.Items.Add("");

            var termStore = session
                .TermStores
                .FirstOrDefault(ts => ts.Groups.Any(g => g.Name == TaxonomyName.Value));
            try
            {
                var group = termStore.Groups[TaxonomyName.Value];
                foreach (var ts in group.TermSets)
                {
                    if (!ts.IsAvailableForTagging) continue;

                    AddTerms(site, termStore, ts.Id, ts.Terms);
                }
            }
            catch (NullReferenceException) { OfficeDropdown.Items.Add("ERROR: Check your Org Term Store Name"); }
            catch (ArgumentOutOfRangeException) { OfficeDropdown.Items.Add("ERROR: Check your Org Term Store Name"); }
        }
    }

    private void AddTerms(SPSite site, TermStore termStore, Guid tsId, TermCollection coll)
    {
        foreach (var t in coll)
        {
            if (t.IsAvailableForTagging)
            {
                var wssIds = TaxonomyField.GetWssIdsOfTerm(site, termStore.Id, tsId, t.Id, true, 1000);

                if (wssIds.Length != 0)
                {
                    var id = wssIds[0];
                    var validatedString = string.Format("{0};#{1}{2}{3}", id, t.Name, TaxonomyField.TaxonomyGuidLabelDelimiter, t.Id);
                    OfficeDropdown.Items.Add(new ListItem(t.Name, validatedString));
                }
                else
                {
                    int id = -1;
                    var value = new TaxonomyFieldValue(SPContext.Current.Web.AvailableFields[new Guid("{a64c1f69-c0d6-421a-8c8a-9ef8f459d7a2}")]);
                    value.TermGuid = t.Id.ToString();

                    var dummy = value.ValidatedString;
                    if (dummy != null)
                        id = value.WssId;

                    var validatedString = string.Format("{0};#{1}{2}{3}", id, t.Name, TaxonomyField.TaxonomyGuidLabelDelimiter, t.Id);
                    OfficeDropdown.Items.Add(new ListItem(t.Name, validatedString));
                }
            }
            AddTerms(site, termStore, tsId, t.Terms);
        }
    }

UPDATE:

The bug was in the TaxonomyField. I was accessing terms cross site collection and the IDs hadn't been generated. Also look out for TermStore IDs not being the same cross site collection (and know where you are calling from and where you are calling to!)

Answer 1

Here are some suggestions.

1. Pull up ULS Log Viewer and study the logs, if you hit the page and get that error, it should be logged there.

2. Check the application event logs on the web front-end server(s).

3. Have you also tried attaching to the W3P.exe process and debug the solution? (Assuming it's not the production environment of course).