Synapse 3 doesn't open on Windows 10

TL;DR - Go to Fix

So I recently brought a Razer Cynosa Lite, a low-ish end computer keyboard, as a bit of a stopgap to fill the void before I find the time to hand wire a nice QMK-compatible..

Razer keyboards come with a bit of software called Synapse 3 - on plugging the keyboard in, the software installs. Everything seemed to install okay, but then the software wouldn't open.

Some Googling of the problem returned a lot of results, and I immediately regretted buying the keyboard, even if I didn't really care about the software - it was more that Razer didn't really seem to have a fix.

Issue #

• Right clicking on the "Razer Central" icon and selecting "Synapse".
• Sometimes the Synapse splash screen would appear and then immediately disappear, other times nothing would happen at all.

Diagnosis #

• Looking in Task Manager confirmed the Synapse process was running
• Services showed all the relevant Razer services were running
• Checked event viewer

Event Viewer #

So far, nothing was giving any sort of indication of any problems - until I looked in the Event Viewer.

Checking the recent entries in Windows Logs -> Application showed the Razer Central Service and the Synapse 3 Web Service stopping/starting in time with me restarting the services. Annoyingly no errors though...

Event Viewer -> Windows Logs -> Application

Windows Logs -> System had a fair few errors though (but really, when doesn't it?) - the HttpEvent errors caught my eye, as they lined up with the Synapse 3 Web Service being restarted...

Event Viewer -> Windows Logs -> System

The error detail was something I'd not seen before:

Unable to bind to the underlying transport for [::]:5426. The IP Listen-Only list may contain a reference to an interface which may not exist on this machine. The data field contains the error number.

No idea what the IP Listen-Only list is, so some Googling later and I'd worked out a potential fix.

Fixing Synapse 3 #

I'm not sure if it's required, but its probably a good idea to close any Razer applications - you can do this by right clicking on the Razer Central icon in the notification area (down by the clock) and selecting Exit All Apps.

We first need to open up an administrative command prompt by searching cmd, right clicking on it and selecting Run as administrator.

IPv6 #

If your error says something like Unable to bind to the underlying transport for [::]:5426, this bit is for you and you don't need to follow the steps under IPv4 below.

We can then add :: (any IPv6) to the IP Listen-Only list by running the command:

netsh http add iplisten ipaddress=::

You should get the following if successful:

IP address successfully added

IPv4 #

If your error says something like Unable to bind to the underlying transport for 0.0.0.0:5426, this bit is for you and you don't need to follow the steps under IPv6 above.

We can then add 0.0.0.0 (any IPv4) to the IP Listen-Only list by running the command:

netsh http add iplisten ipaddress=0.0.0.0

You should get the following if successful:

IP address successfully added

Restart services and test #

We now need to restart the Razer Central Service.

First, open the Services manager by searching for services.msc, right click on it and select Run as administrator.

Find the Razer Central Service, right click on it and select Restart.

You'll see this prompt:

Click Yes, and after a moment both services will restart.

Try opening Razer Synapse again and see if that's resolved it - I'd recommend running Synapse as an administrator (as recommended by Razer).

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