Steam error game validating
For various PC problems, we recommend to use this tool.
This tool will repair common computer errors, protect you from file loss, malware, hardware failure and optimize your PC for maximum performance.
Delete the folder and any state_570_###.patch files to restart the download again.
Make sure that the download is paused and right click Dota 2, click properties and a new window will open.
Click the local files tab and you should see an option to verify integrity of game cache.
If the Validator reports an error that you don't think is an error, first make sure it actually does work and then report it to the forum thread, where Jamie550 will make the necessary corrections as soon as practically possible.
In a similar way, if you discover a bug that wasn't detected by the Validator and cost you some time, report it as well!