Friday, May 25, 2012

Setting LDAP parameter to invalid value caused strange error

I was working on a web based application using C# and ran into a bit of a strange error.  I'm using an LDAP to try and set the option "Require user to change password at next login"  for an Active Directory account.  A small typo resulted in a strange error that lead me to waste some time today.  Thought I'd share to hopefully prevent others from having the same issue.  The error I received was:

A device attached to the system is not functioning. (Exception from HRESULT: 0x8007001F)

The snippet of relevant code:

    public bool RequireUserToChangePwd(bool force)
        bool success = false;

            DirectoryEntry user = loadSpecificEntry();
            if (user != null)
                if (force)
                    user.Properties["pwdLastSet"].Value = 0;
                    user.Properties["pwdLastSet"].Value = 1;
                success = true;
        catch (Exception ex)
            tossFormattedExceptionMessage("Unhandled error requiring force password change",ex);

        return success;

The exception was happening on the call to CommitChanges();   It was happening because the "pwdLastSet" property only has two valid values  0  and  -1  so when I called this method with force = false the exception was being tossed.   Needless to say the error message "A device attached to the system is not functioning" is a bit misleading.   Changing the code to supply the proper value of -1 resolved the issue.  I imagine this error could potentially show up in when using invalid values for other properties being modified using LDAP.  If you're reading this, hopefully I've saved you some time.


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