The Dissolve tool is not working for me when I use ArcGIS Desktop 10 to dissolve a shapefile.

It says:

ERROR 999999: Error executing function.

It works perfectly when I use version 9.3.

Any help?


4 Answers 4


I have found that not all tools work when your geoprocessing environment is set to run in the background. I believe that Dissolve may be one of these. Change you GP environment to Disable Background Processing and then give it a try.

I have not tested this but may be worth a try

  • You're a genius! It worked perfectly
    – Kevin
    Commented Oct 12, 2010 at 1:39
  • 4
    @Kevin Don't forget to accept CDBrown's answer, since this answered your question. It's always nice to give thanks where it's due. Commented Oct 12, 2010 at 1:56

Try this: Run Repair Geometry 1st and then run Dissolve.


The 99999 error can be caused by any number of reasons; system resource availability or dataset issues are a couple possibilities. While disabling background processing may seem to have solved the immediate problem it actually is only a workaround to another problem. All tools (aside from the 5 or 6 which absolutely cannot run in the background) do function through background processing - there however might be one off cases or bugs for a particular situation which causes tools not to run. In general, the dissolve tool functions fine through background processing.


I have found that I need to go into the environments and specify that the processing extent is the extent of the shape file in question. For some reason the default extent is off.

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