Samples do not work in Firefox because of a connection error

Problem

Firefox reports 'Unable to establish connection to SigCaptX'

Solution

Verified in Firefox version 99.

STU SigCaptX requires access to https://localhost:9000 by default. It is possible to configure a different port number, but this doesn't cure the problem described below.

Firefox considers the attempted connection to localhost to be a security breach and refuses to allow it.

In order to remedy this it is necessary to tell Firefox to ignore the security risk as described below:

1. Navigate to https://localhost:9000 in the Firefox browser.

2. An error message should appear saying that there is a potential security risk ahead - see first screenshot below

3. Click on the "Advanced" button at the bottom right of the dialog box to display the window shown in the second screenshot below

4. On the second dialog window click the button labelled "Accept the Risk and Continue"

5. It will look as if nothing is happening apart from a moving blue dot at the top left-hand corner of the Firefox window

6. Reload the sample into Firefox and it should work