Backload 1.9.3.1 file upload handler generating 500 error out of the blue - nothing changed on server

Question

We've been using backload in production for about 2 years without any issues. All of a sudden this morning uploads no longer work. There were no server/software/config changes and I cannot see anything wrong. I checked permissions, disk space etc. but no luck. In fact, it turned out that the files are actually being uploaded correctly! All the failed attempts are there in my upload directory but somehow there is a failure before the upload handler can send the json response with the file info.

FYI, I have another application on the same server that (actually a demo version of the other application - the same in every respect except for the directory to which files are saved (different directory on same drive)) that works perfectly.

I enabled tracing so I could try and get a handle on what is going wrong, but that is also fail - after initially creating the log files and writing the first few lines about backload component initialization, logging stops. Nothing is logged for any uploads.

I don't expect anybody to magically solve my issue (but if you do I may ask you to marry me) but if anybody has any advice on where to look for potential problems, that would be helpful. Also, if you have any insights as to why tracing is not working, that would be very helpful as well. Web.config tracing settings follow:

  <system.diagnostics>
    <trace autoflush="true">
    </trace>
    <sources>
      <source name="Backload" switchName="traceLevel">
        <!-- name must be "Backload".  -->
        <listeners>
          <!-- Trace output can be accessed http://[webapp root]/trace.axd -->
          <add name="WebPageTraceListener" type="System.Web.WebPageTraceListener, System.Web, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
          <add name="logfile" />
          <!-- Trace output to log file, but only errors (see filter below) -->
          <add name="xmlfile" />
          <!-- XML output for the Microsoft Service Trace Viewer -->
        </listeners>
      </source>
    </sources>
    <sharedListeners>
      <add name="logfile" type="System.Diagnostics.TextWriterTraceListener" initializeData="C:\www\dad.prod\logs\backload.log" traceOutputOptions="DateTime">
        <!--<filter type="System.Diagnostics.EventTypeFilter" initializeData="Error" />-->
        <!--Only log errors in this listener-->
      </add>
      <add name="xmlfile" type="System.Diagnostics.XmlWriterTraceListener" initializeData="C:\www\dad.prod\logs\backload.svclog" traceOutputOptions="DateTime" />
      <!--traceOutputOptions="DateTime,LogicalOperationStack,Callstack" />-->
    </sharedListeners>
    <switches>
      <!-- Set the level at which tracing is to occur. Example: <add name="traceLevel" value="Error" /> -->
      <!-- Valid levels are Off, Critical, Warning, Information, Verbose. Optional: ActivityTracing -->
      <!-- To turn tracing off set the value attribute to "Off". Example: <add name="traceLevel" value="Off" /> -->
      <add name="traceLevel" value="Information, ActivityTracing, Verbose, Critical, Error" />
    </switches>
  </system.diagnostics>

Thank you

Answer 1

So...I recycled the app pool a couple times (which I was loathe to do because it kicks people out of the application) and things seem to have fixed themselves - uploads now work.

I had touched the web.config a few times (adding the tracing settings) which I thought caused a recycle but it didn't work. Only when I went into IIS manager and manually recycled the app pool did things start to work.

Thanks