Hello, as the title says I am trying to join a CSV file to a feature class and I keep getting an error 999999. At first, I thought it was because field types were different so once I had them matching up properly I assumed the join would go through, but I still get the same error. It should be a fairly simple join so I am not sure what I am missing that is causing this error to come up. I would appreciate any advice on the matter.
show your inputs. it could be something with a particular column or a row.
Try making the csv into a geodatabase table first, then try the join is another option
If you are trying to join string fields together make sure your .csv file does not have a length greater than 255
If it does then technically even though it is still a string but it is a type not supported. One way to determine that is to import the .csv into a database and look at the properties. .csv fields can have up to 32767 characers.
Like DanPatterson said, add your csv to the Contents pane and then immediately export it to a geodatabase table. Joining a Feature Class to a csv file directly is prone to errors, which is why everyone recommends exporting the csv to a geodatabase table. If you join a Feature Class to a csv and check the "Index Joined Fields" checkbox, you will always get a ERROR 999999.
It would be nice if we had better error messages when joining Feature Class to a csv. ESRI should disable the ability to join Feature Class to csv altogether. Having a right click option to import CSV to Geodatabase table quickly would be a nice alternative.