"Cannot connect to license server system. The license server has been modified."
If you want to implement the SolidWorks host file block fix successfully, follow this checklist:
If you still face errors, your issue is not the Hosts file. It is either a corrupt installation (run the SolidWorks Rx diagnostics) or a broken license file (regenerate your .lic file).
The Hosts file is a powerful tool, but it is a scalpel, not a hammer. Used correctly, it silences validation noise. Used blindly, it breaks your internet resolution. Edit wisely.
Need more help? Check the SolidWorks official forums or your local reseller for legitimate network licensing support.
Windows protects the Hosts file by default. You must be an administrator to modify it.
Locate the File: Navigate to C:\Windows\System32\drivers\etc. Modify Security: Right-click the hosts file and select Properties. Go to the Security tab and click Edit.
Select your user account and check the box for Full Control or Modify under the Microsoft Learn guide. Click Apply and OK. 2. Edit the Hosts File to Fix Blocks
Once permissions are granted, you can remove lines that might be blocking SOLIDWORKS communication.
Open Notepad as an Administrator (Search for Notepad, right-click, and select "Run as Administrator").
In Notepad, go to File > Open and browse to C:\Windows\System32\drivers\etc. Change the file type filter to All Files (.). Open the hosts file.
Look for any entries related to solidworks.com or your internal license server IP (e.g., 127.0.0.1 license.solidworks.com).
Fix: Delete these lines or add a # at the beginning of the line to comment them out. Save the file and restart SOLIDWORKS. 3. Check Firewall Outbound Rules
If the Hosts file is clear but you still face blocks, your firewall may be preventing the connection.
Verify Rules: Ensure there isn't an Outbound Rule blocking the SOLIDWORKS executable (SLDWORKS.exe).
Configuration: As detailed in community guides, you can manage these settings via the Windows Defender Firewall with Advanced Security menu by checking the "Outbound Rules" section. 4. Quick SOLIDWORKS Fixes
If the issue is related to file corruption rather than connectivity: solidworks host file block fix
Repair Function: Use the built-in SOLIDWORKS Repair Tool when prompted by a corruption dialog box.
Force Rebuild: Use Ctrl + Q to perform a deep rebuild of the entire document from the ground up.
Are you experiencing a specific License Error code (like -15 or -8) that led you to the hosts file? 11 SOLIDWORKS CTRL Key Shortcuts to Start Using Today
SOLIDWORKS Host File Block Fix: A Comprehensive Guide
Are you experiencing issues with SOLIDWORKS due to a blocked host file? Do you see an error message indicating that the software is unable to connect to the license server or access certain features? You're not alone. In this article, we'll explore the SOLIDWORKS host file block fix, a common problem that affects many users. We'll provide a step-by-step guide on how to resolve the issue and get your SOLIDWORKS software up and running smoothly.
What is a Host File?
A host file is a text file used by the operating system to map hostnames to IP addresses. It's a crucial file that helps your computer communicate with other devices on a network. The host file is usually located in the C:\Windows\System32\drivers\etc directory on Windows systems.
What Causes a Host File Block in SOLIDWORKS?
When you install SOLIDWORKS, it may create entries in the host file to facilitate communication between the software and the license server. However, sometimes these entries can become corrupted or blocked, causing issues with the software. Here are some common reasons that can lead to a host file block:
Symptoms of a Host File Block
If you're experiencing any of the following symptoms, it's possible that your host file is blocked:
SOLIDWORKS Host File Block Fix: Step-by-Step Guide
To fix the host file block, follow these steps:
Method 1: Manually Editing the Host File
Method 2: Using the SOLIDWORKS License Server Tool
Method 3: Resetting the Host File
Additional Troubleshooting Steps
If the above methods don't resolve the issue, try the following:
Conclusion
In the context of SOLIDWORKS, "fixing" the host file typically refers to resolving connectivity issues between a client machine and a server (such as PDM or License servers) by manually mapping IP addresses to server names. This is often used as a short-term workaround when DNS resolution fails. Troubleshooting Host File Blocking & Connectivity
If SOLIDWORKS is unable to reach its server or you cannot edit your hosts file, check the following common causes and solutions:
Antivirus/Security Software Blocking: Programs like Webroot, ZoneAlarm, and SentinelOne often protect the hosts file from being modified.
To fix this, you must disable the "Lock Hosts File" or "Prevent modifications" setting within your security software's management console.
Read-Only Attribute: The file itself may be set to read-only.
Navigate to C:\Windows\System32\drivers\etc, right-click the hosts file, select Properties, and uncheck Read-only.
Insufficient Permissions: You must use administrative privileges to save changes.
Search for Notepad in the Start Menu, right-click it, and select Run as Administrator before opening the file. How to Configure the Local Hosts File Follow these steps to manually map your SOLIDWORKS server:
Open Notepad as Administrator: Right-click the app and select Run as Administrator.
Navigate to the File: Go to C:\Windows\System32\drivers\etc. Ensure the file type filter is set to All Files (.) to see the extensionless "hosts" file.
Add the Server Entry: On a new line at the bottom, type the IP Address, then a Tab space, then the Server Name. Example: 192.168.1.100 PDMServerName.
Flush DNS: After saving, open the Command Prompt and type ipconfig /flushdns to clear old resolution data. Related Fixes for Common SOLIDWORKS Blocks
Installation Manager (Blank Screen): If the installer is blocked, it is often because Windows has "blocked" the downloaded files. Right-click the .html files in your installation folder (e.g., \sldim\lang\english\HTML\), select Properties, and click the Unblock button if present. "Cannot connect to license server system
License Server Communication: If the host file is correct but you still can't connect, ensure TCP ports 25734 and 25735 are open in your Windows Firewall for the SolidNetWork License (SNL) Manager.
This method is typically used to prevent SolidWorks from "phoning home" to validate a license. Please note: This guide is for educational purposes. Using this fix with an unlicensed, cracked, or unauthorized version of SolidWorks is a violation of the Dassault Systèmes license agreement.
The hosts file is a plain text file that maps hostnames to IP addresses. By adding lines like:
127.0.0.1 license.solidworks.com
...you are telling your computer to "look" for the SolidWorks license server on your own hard drive instead of on the internet.
In theory, this prevents SolidWorks from "phoning home" to check if your license key is valid or if it has been blacklisted.
Here is the irony. In 2020 and beyond, Dassault Systèmes (SolidWorks' parent company) updated their licensing kernel. They introduced a "Self-Healing" mechanism. When SolidWorks starts, it now:
If the validation fails (due to a firewall or offline status), the software triggers a Network License Hang. The "fix" hackers used is now the cause of legitimate corporate failures.
Furthermore, malicious antivirus software and "PUP" (Potentially Unwanted Program) cleaners sometimes see leftover entries from old cracks and "fix" them by blocking SolidWorks altogether. Suddenly, your legit license is broken by a ghost from the past.
Use this guide if SolidWorks (or SolidWorks license activation/serial validation) is being blocked by your hosts file, DNS, or local redirections. These steps cover Windows 10/11. Proceed with admin rights and back up files before editing.
Before editing the host file, you should try these safer fixes:
Open File Explorer and navigate to:
C:\Windows\System32\drivers\etc\
You will see a file named hosts (no extension).
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:
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.