I'm still having trouble with the dissolve tool and I've tried all of the solutions offered here including moving the process from the background and repairing the geography. I've also tried amending the spatial index and narrowing the dissolve area down considerably.
Is there anything that I'm missing?
Right now when I run the tool, it jumps right to 33% complete and stalls out. If I wait for an hour or so it gives me the 99999 error (edited to clarify, I am also getting the Invalid Topology error). I'm doing this project for work and waiting an hour each time isn't working for me (or my boss) anymore.
Best Answer
Assuming you are getting the "Invalid Topology" error you need to make sure that all geometry in this feature class is correct. Make sure the layer is in a File Geodatabase Feature Class format. Run the "Repair Geometry" then try DISSOLVE again.
Dissolve can create VERY large features from a large amount of small features and it can be a very memory intensive operation and thus take a very long time depending on the complexity of the input feature class and the dissolve parameters.
There are also other considerations when running dissolve explained in detail in the Dissolve Help and the How Dissolve Works.
When you feel that you have complied with all the usage requirements for the dissolve operation as outlined in the Help Usage article, you can submit a request for Support Assistance with ESRI. They have been very quick to respond lately. (within 24 hours) They will run the same steps on their end and provide you with solutions. You will need your ESRI customer number to request support.