Solidworks Host File Block - Fix

The Ultimate Guide to the SolidWorks Host File Block Fix: Stop License Errors & Crashes SolidWorks is the gold standard for CAD design, but few things are more frustrating than being in the zone, modeling a complex assembly, and suddenly being hit with a License Error (-15, -97, or -5) or a complete crash. Often, the culprit isn't corrupt software or bad hardware—it is your own Windows Hosts File . If you are searching for the "SolidWorks host file block fix," you likely fall into one of two categories:

You are a legitimate user trying to prevent SolidWorks from "phoning home" during a network license issue. You are using a network license file (legitimately or otherwise) and need to force the software to look at a local server instead of the internet.

Regardless of your scenario, manipulating the Hosts file is a standard system administration trick to redirect or block network traffic. This article will explain why this fix works, how to do it safely, and what to do when it fails.

Disclaimer: This guide is for educational purposes regarding network administration and troubleshooting legitimate license server errors. Bypassing paid licensing agreements violates SolidWorks' Terms of Service (TOS). We do not condone software piracy. solidworks host file block fix

Part 1: What is the Windows Hosts File? (And Why SolidWorks Hates It) Before we click "Save," let’s understand the battlefield. The hosts file is a plain text file used by your operating system to map hostnames to IP addresses. It has priority over DNS (Domain Name System). When you type www.google.com , your PC checks the Hosts file first. If it finds an entry, it goes there without asking the internet. How SolidWorks uses the internet: When you start SolidWorks, it checks for three things:

License Validation: Is this copy legitimate? Telemetry: Sends usage data back to Dassault Systèmes. Updates: Checks for patches.

The "Block" Fix: By editing the Hosts file, you tell your computer to send SolidWorks' validation requests to a dead end (usually 127.0.0.1 - your own computer) instead of the real Dassault servers. This stops the software from realizing it might be running on a floating license that expired, or prevents it from turning off features because it cannot reach the primary license server. The Ultimate Guide to the SolidWorks Host File

Part 2: Why You Need the Host File Block Fix (The Symptoms) You are here because you are seeing specific errors. Here are the top three symptoms that the Hosts file fix resolves: 1. License Error: -97, 121 "SolidWorks cannot connect to the license server. The server may be down or you are not connected to the network."

Cause: SolidWorks tried to ping the license server (e.g., 25734@localhost or a remote server) but the DNS lookup failed or the traffic was blocked by a firewall. Fix: Redirects traffic internally.

2. License Error: -15, -5 "Cannot connect to license server system. The license server has been modified." You are using a network license file (legitimately

Cause: Your system time is off, or the software attempted to validate a floating license against the internet and failed. Fix: Prevents the software from looking for a "kill switch" validation online.

3. SolidWorks "Freezes" on Splash Screen You double-click the icon. The splash screen appears. The loading bar gets stuck at 75%... and stays there forever.