ArcGIS Identity tool giving ERROR 999999

ArcGIS Identity Tool Throwing Error 999999? Let’s Figure It Out.

The ArcGIS Identity tool. It’s a workhorse. It lets you smash two feature classes together, merging their attributes based on location. Super useful for all sorts of spatial analysis, right? But then BAM! Error 999999. That dreaded, vague error that basically says, “Something went wrong, good luck figuring it out.” Been there? We all have. This guide is all about cracking the code on this error when you’re trying to use the Identity tool.

What’s the Deal with Error 999999?

Okay, so Error 999999 in ArcGIS? It’s the ultimate “something’s not right” message. It means the tool choked, but it’s not telling you why. When you’re wrestling with the Identity tool, this can be super annoying. It’s like a car mechanic telling you the engine’s broken without saying what part is busted. You’ve gotta play detective.

Digging into the Usual Suspects (and How to Fix Them)

So, what usually causes this headache? Let’s break it down:

• Data Gremlins (aka Corrupted Geometry): This is a big one. If your data’s wonky – maybe it’s got null geometry (empty shapes), tiny segments, or those self-intersecting polygons that drive everyone nuts – the Identity tool is gonna throw a fit. I’ve seen this happen so many times.

  • The Fix: Before you even think about running the Identity tool, run the “Repair Geometry” tool on both of your input feature classes. Seriously, do it. This tool is like a data doctor, patching up all those geometric boo-boos.

• Naming Nightmares: ArcGIS is picky about names. You can’t use weird characters, start with a number, or use reserved words like “ADD” or “TABLE.” Plus, make sure you have permission to write to the output location. Simple, right? But easy to miss.

  • The Fix: Double-check your output name and path. Make sure they play by ArcGIS’s rules. Try creating a file manually in that folder to make sure you can actually write to it.

• Dataset Size Matters (a Lot): Trying to process a massive dataset can overwhelm your system. Think of it like trying to drink from a firehose.

  • The Fix: If you’re dealing with a huge dataset, chop it up into smaller pieces using the Clip tool. Process those smaller chunks separately. Also, crank up the parallel processing factor in your settings to use more of your computer’s horsepower.

• Spatial Reference Shenanigans: If your feature classes are speaking different coordinate system languages, the Identity tool gets confused.

  • The Fix: Make sure both datasets have a defined spatial reference. If they’re different, project one to match the other before running the Identity tool. If you’re using some custom spatial reference, maybe try switching to a standard one to see if that solves the problem.

• Topology Troubles: Overlapping polygons can cause topology errors, especially with large datasets.

  • The Fix: Simplify the identity feature class by dissolving boundaries or removing unnecessary detail. Consider the complexity of the identity polygon feature class, especially if it contains a large number of parts or areas of overlap.

• Software Bugs (Ugh): Sometimes, it’s just the software being buggy. It happens.

  • The Fix: Make sure you’re running the latest version of ArcGIS and have all the patches installed. If you suspect a bug, contact Esri support. They might have a workaround or be working on a fix.

• Licensing Lapses: Not super common, but sometimes licensing issues can pop up as generic errors.

  • The Fix: Double-check that your ArcGIS license is valid and that you have the right extensions enabled.

• Temporary File Glitches: Sometimes temporary files can cause issues.

  • The Fix: Close ArcGIS, clear out your temp folder (usually C:\Users\{yourUserName}\AppData\Local\Temp), restart ArcGIS, and try again. It’s a simple thing, but it can work wonders.

Pro Tips for Identity Tool Success

Want to avoid Error 999999 in the first place? Here’s my advice:

• Check Your Data: Use the “Check Geometry” tool religiously.
• Simplify, Simplify, Simplify: Less complex geometries mean less processing time and fewer headaches.
• Divide and Conquer: For huge datasets, process them in smaller chunks.
• Attribute Awareness: Think about which attributes you really need to transfer. More attributes mean more processing.
• Test the Waters: Before running the tool on your entire dataset, try it on a small subset first.
• Stay Updated: Keep your ArcGIS software up-to-date.
• Parallel Processing: Set the parallel processing environment variable to 100 to take advantage of parallel processing.

A Quick Note on ArcGIS Pro

ArcGIS Pro does things a little differently than ArcMap. The old “Identify” tool is gone, replaced by the Attributes pane and pop-ups. This doesn’t change how the Identity geoprocessing tool works, but it’s good to know when you’re exploring your data.

Wrapping Up

Error 999999 with the Identity tool? Yeah, it’s annoying. But with a little detective work and these tips, you can usually track down the problem and get back to your analysis. And remember, when in doubt, Esri’s documentation and support are your friends. Good luck!