A web app I am building seems to be broken in Firefox. It loads ok the first time, but not the second. I checked the console and I found I get an error message that says: Loading failed for the <script> with source “https://cdn.jsdelivr.net/npm/vue/dist/vue.js”. I tried loading the URL https://cdn.jsdelivr.net/npm/vue/dist/vue.js in another tab, and it loads ok the first time, but if I reload it I get a security error: Did Not Connect: Potential Security Issue and when I hit advanced I see Someone could be trying to impersonate the site and you should not continue. [...] Error code: SEC_ERROR_UNKNOWN_ISSUER and under view certificate: https://cdn.jsdelivr.net/npm/vue/dist/vue.js Peer’s Certificate issuer is not recognized. Neither Chrome nor Safari seem to be affected. Another weird symptom is that pictures on stackoverflow are all broken. I appreciate any help - thanks.