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  • Avatar12posts34karma

    Missing Lucene.Net assembly

    patrick iversen started this topic January 7, 2011 @ 02:51

    Hi there,

    I have a umbraco 4.5 with .net 3.5 and recently upgraded the server to .net 4, and the site worked great until now. The site is very slow to load and then finally stops, displaying the 503 error and has stopped the application pool. If I restart the application it starts again but the outcome is the same.  If I check the event log in IIS 7 the only entry is "Message: Unable to find assembly 'Lucene.Net, Version=, Culture=neutral, PublicKeyToken=null'.  I've checked the installation and the dll is present along with the correct version, and the site ran fine until this error came along.  Has anyone experienced this behavior before and maybe fixed it in some way? 

  • Avatar3309posts6220karma2015 MVP
    adminMVPComment with ID: 59653
    Ismail Mayat posted this reply January 7, 2011 @ 05:01

    Patrick can you double check your permissions.



  • Avatar12posts34karma
    Comment with ID: 59843
    patrick iversen posted this reply January 10, 2011 @ 10:16

    Hi Ismail,

    Permissions seems to be set. Network service has r/w to all the folders and files Umbraco requires.

  • Avatar10077posts18998karma2015 MVP
    CoreadminMVPComment with ID: 59847
    Jan Skovgaard posted this reply January 10, 2011 @ 10:31

    Hi Patrick

    What happens if you set the "modfiy" permission as well?


  • Avatar12posts34karma
    Comment with ID: 59853
    patrick iversen posted this reply January 10, 2011 @ 10:41

    Hi Jan,

    Jep modify and execute and everything but "special permissions".

  • Claus Witt posted this reply January 14, 2011 @ 03:17


    Just saw a link to this issue from http://twitter.com/greystate ... 

    It reminds me of an error in an old .net application I used to develop and maintain. Application pools - back then - would fail when having applications/libraries compiled with different versions of the .net framework. This sounds to me to be the same issue - but since I have not worked professionally with .net solutions in a couple of years now, I am not sure. But it might be something to look into. 


  • Avatar12posts34karma
    Comment with ID: 60646
    patrick iversen posted this reply January 14, 2011 @ 03:59

    Hey guys, thanks for the solutions. Due to time constraint I ended up doing a reinstall with .net 4 version of umbraco and copied the files I needed, and now it's back up and running. Sure was a weird issue,  but probably had to do with compiled version, that broke when the server got .net 4 and still used the .net 2 pool setting.  I've used the same umbraco installation for a lot of other sites with the same configuration and have never had any issues like this before.

    Anyway, thanks for the many suggestions :).


  • Avatar796posts609karma
    Comment with ID: 89637
    Greg posted this reply September 18, 2011 @ 06:11

    Same issue here.. works perfectly on my local dev box, but on the server it keeps crashing the app pool.

    Has anybody resolved this issue?  It's happening on a 4.7.0 umbraco site running on windows 2008 iis 7 (integrated and classic mode).

    very frustrating :|

  • Avatar68posts141karma
    Comment with ID: 110891
    Scott posted this reply March 14, 2012 @ 07:37

    Did anyone ever come up with a resolution for this? I am have the exact same error on 1 of about 10 umbraco 4.7 sites that I have. Its very slow to load, often failing because the app pool stops. And in my application event log I see the same 2 errors over and over:

    An unhandled exception occurred and the process was terminated.
    Application ID: DefaultDomain
    Process ID: 9024
    Exception: System.Runtime.Serialization.SerializationException
    Message: Unable to find assembly 'Lucene.Net, Version=, Culture=neutral, PublicKeyToken=null'.
    and then
    Application: w3wp.exe
    Framework Version: v4.0.30319
    Description: The process was terminated due to an unhandled exception.
    Exception Info: Lucene.Net.Index.MergePolicy+MergeException

  • Avatar68posts141karma
    Comment with ID: 110898
    Scott posted this reply March 14, 2012 @ 08:28

    I ended up resolving my own problem.

    I removed App_Data/temp/ExamineIndexes and it rebuilt it and my problem was resolved.

  • Avatar195posts439karma
    Comment with ID: 119391
    Jon Dunfee posted this reply June 12, 2012 @ 08:13

    Just went through a migration from one location to another.  I removed the contents of App_Data/TEMP/ExamineIndexes and after a minute or so of watching the browser spinner (while the Lucene cache was being rebuilt) the site came up.


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