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  • XP Pro IE and error InvalidCastException

    I support an office that has 10 or so computers that all run IE7 or IE6 and either XP Pro or XP home addition and one of the computers has recently started having problems emails from a particular webpage where it is supposed to lauch outlook. It works on all other computers but this one has me stumped. THe computer has recently been upgraded to IE 7 however I tried uninstalling that and running 6 again and that didn't work.

    The error is coming from a web app in the MLS for realestate. "Cast from type 'DBNULL' to type 'string' is not valid exception details :System.InvalidCastException.

    Has anyone every come across this? I don't get it on anyo ther computer although it appears to be an error returned from the server it has to be something client specific on this workstation. I loaded the .Net 2.0 library yesterday but that didn't help anything. if anyone has any thoughts I would appreciate it

    thanks

  • #2
    Re: XP Pro IE and error InvalidCastException

    Originally posted by Tigershark
    one of the computers has recently started having problems emails from a particular webpage where it is supposed to lauch outlook.
    The above quote has me confused as I can't work out what you mean (Outlook launching from a webpage could mean you are using Outlook Web Access, in which case you are not using Outlook). Could you please provide more detail about the problem and avoid using abbreviations like MLS (whatever it stands for). Thanks.
    1 1 was a racehorse.
    2 2 was 1 2.
    1 1 1 1 race 1 day,
    2 2 1 1 2

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    • #3
      Re: XP Pro IE and error InvalidCastException

      there is a button on the Multiple Listing Service (Real Estate Site) and by clicking the send link it is supposed to launch your email client. MS Outlook. Instead it returns the error below, it works on every other workstation in the office but one

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      • #4
        Re: XP Pro IE and error InvalidCastException

        My mom is a former Real Estate agent, so I know what you are talking about - unfortunately, back then it was all dialup access, and everything was done internally.

        On this particular machine, have you tried re-installing Outlook / Office (you might could try a repair first) to see if that fixes it?

        Also, have you contacted your local MLS board to see if they might have any solutions for you

        For those needing edification, MLS stands for Multiple Listing Service - a service for realtors throughout the US that houses all current listings, regardless of realty company affiliation, so that any realtor with any company can look at listings in any generalized area, although usually within your own locale. It has obviously grown since the time my mother used to use it - it used to require making a dialup connection to the local MLS Server to peruse listings, which you could search for using a variety of keywords, such as 3.5 baths, 4 BR, fireplace, etc.


        Since nine of the 10 machines are not exhibiting this symptom, you're right, tiger, it is on that one workstation - however, I wonder if something else is blocking the call from IE to Outlook - to narrow it down, could you try Firefox 3 (it gets released Tuesday, but the RC 3 that is out now is pretty much the same thing) and see if it makes a difference? Or does the MLS site require the use of ActiveX controls?
        Last edited by johnlgalt; 15th June 2008, 04:45.
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        • #5
          Re: XP Pro IE and error InvalidCastException

          Originally posted by tigershark View Post
          I support an office that has 10 or so computers that all run IE7 or IE6 and either XP Pro or XP home addition and one of the computers has recently started having problems emails from a particular webpage where it is supposed to lauch outlook. It works on all other computers but this one has me stumped. THe computer has recently been upgraded to IE 7 however I tried uninstalling that and running 6 again and that didn't work.

          The error is coming from a web app in the MLS for realestate. "Cast from type 'DBNULL' to type 'string' is not valid exception details :System.InvalidCastException.

          Has anyone every come across this? I don't get it on anyo ther computer although it appears to be an error returned from the server it has to be something client specific on this workstation. I loaded the .Net 2.0 library yesterday but that didn't help anything. if anyone has any thoughts I would appreciate it

          thanks

          It's definitly an client side error because if this error would occur serverside then you would not get to see this error on the clientscreen.

          The error you discribe is caused because some application OR component is trying to make an illegal cast. (Casting is converting the type of an object from one kind to an other and is used very much in C++/C# like programming enviroments).

          "Cast from type 'DBNULL' to type 'string' is not valid
          From MSDN :
          The DBNull class represents a nonexistent value. In a database, for example, a column in a row of a table might not contain any data whatsoever. That is, the column is considered to not exist at all instead of merely not having a value. A DBNull object represents the nonexistent column.
          I.O.W. the program is trying to convert an value to an string, but for some reason the value that it's supposses to convert does not exist in the database, you will have to provide more info to pinpoint the exact problem but it all point's to problems between an component and the DB

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          • #6
            Re: XP Pro IE and error InvalidCastException

            OK, that makes more sense - thanks Ronald.

            I suppose what is happening is that the settings on that machine in IE are a bit more stringent - in that it is not passing the email value from the MLS Web interface to the database, thus Outlook is not getting anything.

            Tiger, can you verify the settings on IE are the same between that machine and another machine in the office?

            Also, does that machine have anything special on it (a different firewall client, antivirus client, Spybot S&D, etc, installed, that may be interfering? If so, try temporarily disabling any such software and see if it makes a difference....
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            • #7
              Re: XP Pro IE and error InvalidCastException

              Firefox produces the same error, the software is identical outside of some a number of MS Security updates, I thought it had something to do with IE 7 but I uninstalled that and removed the updates related to it but same isue, it started a couple of weeks ago and the only thing that changed (so I was told) was IE 7 installed and some security updates installed automatically. The error is actually being thrpwn from the Microsoft.VisualBasic.CompilerServices.StringType. FromObject

              I am kind of at a loss, I would hate to reinstall the OS to fix one bug

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              • #8
                Re: XP Pro IE and error InvalidCastException

                OK, so it worked before and then all of a sudden stopped working?

                Have you by chance performed a malware scan on the machine?
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                • #9
                  Re: XP Pro IE and error InvalidCastException

                  Yes the machine came up clean

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                  • #10
                    Re: XP Pro IE and error InvalidCastException

                    Hmmm - weird- since it is doing it in Fx as well, I wonder if something strange is going on....and since it is seemingly Malware free, I think the next item to check for would be to see if that particular machine needs an Office / Outlook repair....

                    Is the MLS page hard coded to use Outlook only, or whatever the default mail client is?
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                    • #11
                      Re: XP Pro IE and error InvalidCastException

                      It doesn't appear to be I have seen it use Outlook express, Outlook works fine outside of being called from this website, you can lauch it via other websites using the html mailto without a problem

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                      • #12
                        Re: XP Pro IE and error InvalidCastException

                        Hmmm - Try running OE and making it the default and see if it will load OE fine - or you can install a copy of Thunderbird and try that instead, because I think once you uninstall Tb you should be able to relatively easily set Outlook as your default mail program again....
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                        • #13
                          Re: XP Pro IE and error InvalidCastException

                          I will give that a try thanks for the suggestion

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                          • #14
                            Re: XP Pro IE and error InvalidCastException

                            Please post back as to the results, I am honestly not confident that this will do much, other than point the finger back at the browsers and / or something in the OS....

                            Hmmm, speaking of the OS, you might also try SFC /SCANNOW to see if a critical file is missing from the OS itself, thereby disallowing the passing of the information, and thus making Outlook think it is receiving null data....
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                            • #15
                              Re: XP Pro IE and error InvalidCastException

                              I'm sure you probably have already done this (but it hasn't been stated) but have you cleared the cookies and temp files? Have you reset IE to the defaults?

                              http://support.microsoft.com/kb/936213
                              Regards,
                              Jeremy

                              Network Consultant/Engineer
                              Baltimore - Washington area and beyond
                              www.gma-cpa.com

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