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Do not use Notepad shortcuts. Go directly to: C:\Windows\System32\drivers\etc\hosts Note: There is no file extension. It is just called hosts .

Example of a bad line to remove: 127.0.0.1 ://solidworks.com Delete these specific lines.

Open the and navigate to System and Security > Windows Defender Firewall . Click Advanced Settings on the left panel.

#127.0.0.1 license-server (commented out)

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.

This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later.

While the Hosts file fix is a powerful troubleshooting tool, ensuring long-term software stability involves checking that your hardware and security configurations match your edits.

: In the SolidNetWork License Manager , ensure the box "A firewall is in use on this server" is checked so it uses a static port for communication.

If you still cannot connect after updating the hosts file, the block may be at the firewall level:

Are you using a or a network SolidNetWork License (SNL) ?

Fixing "SolidWorks host file block" issues typically involves unblocking the Windows hosts file from security software or manually editing it to resolve server connection problems. This common technical hurdle often prevents SolidWorks PDM or license managers from communicating with their servers. Common Causes for Host File Blocks

To reset it, delete the contents of your current host file and paste the following standard clean layout into your administrator-run Notepad:

If you are seeing errors like (Unable to verify server 25734@localhost) or "Cannot connect to license server," it is highly likely your Hosts file contains a misconfigured entry.

Recent Episodes

Solidworks Host File Block Fix Jun 2026

This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later.

Do not use Notepad shortcuts. Go directly to: C:\Windows\System32\drivers\etc\hosts Note: There is no file extension. It is just called hosts .

Example of a bad line to remove: 127.0.0.1 ://solidworks.com Delete these specific lines.

Open the and navigate to System and Security > Windows Defender Firewall . Click Advanced Settings on the left panel. solidworks host file block fix

#127.0.0.1 license-server (commented out)

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.

This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. This public link is valid for 7 days

While the Hosts file fix is a powerful troubleshooting tool, ensuring long-term software stability involves checking that your hardware and security configurations match your edits.

: In the SolidNetWork License Manager , ensure the box "A firewall is in use on this server" is checked so it uses a static port for communication.

If you still cannot connect after updating the hosts file, the block may be at the firewall level: Can’t copy the link right now

Are you using a or a network SolidNetWork License (SNL) ?

Fixing "SolidWorks host file block" issues typically involves unblocking the Windows hosts file from security software or manually editing it to resolve server connection problems. This common technical hurdle often prevents SolidWorks PDM or license managers from communicating with their servers. Common Causes for Host File Blocks

To reset it, delete the contents of your current host file and paste the following standard clean layout into your administrator-run Notepad:

If you are seeing errors like (Unable to verify server 25734@localhost) or "Cannot connect to license server," it is highly likely your Hosts file contains a misconfigured entry.