Microsoft Teams Connector unable to save configuration - microsoft-teams

Question

I'm trying to build a Microsoft Teams connector that I have sideloaded into my team while developing. I've set up a testing config page on S3 and have pointed my app manifest to it. When I click the save button, it stays stuck on the "Setting up your connector" spinner for a while, before saying "Unable to save connector configuration. Please try again."
The Javascript of the config page should be visible through the S3 link above; my app manifest is below. After looking at a few similar questions, you'll note that the contentUrl is included by wildcard in validDomains.
{
"$schema": "https://developer.microsoft.com/en-us/json-schemas/teams/v1.7/MicrosoftTeams.schema.json",
"manifestVersion": "1.7",
"version": "1.0.0",
"id": "0b73c39a-db1d-43eb-81bd-3813bef33713",
"packageName": "<redacted>",
"developer": {
"name": "Developer",
"websiteUrl": "<redacted>",
"privacyUrl": "<redacted>",
"termsOfUseUrl": "<redacted>"
},
"icons": {
"color": "color.png",
"outline": "outline.png"
},
"name": {
"short": "Test",
"full": "Test"
},
"description": {
"short": "Test notifications",
"full": "Test notifications"
},
"accentColor": "#FFFFFF",
"connectors": [
{
"connectorId": "0b73c39a-db1d-43eb-81bd-3813bef33713",
"configurationUrl": "https://wsk-teams-test.s3.amazonaws.com/teams_configure.html",
"scopes": [
"team"
]
}
],
"permissions": [
"identity",
"messageTeamMembers"
],
"validDomains": [
"wsk-teams-test.s3.amazonaws.com",
"<redacted>"
]
}
I'm not able to get any more detailed information when attempting this via the desktop Teams app, but in the browser I see this error in the console:
2020-09-02T23:05:20.879Z Received error from connectors {"seq":1599086774636,"timestamp":1599087920857,"flightSettings":{"Name":"ConnectorFrontEndSettings","AriaSDKToken":"<redacted>","SPAEnabled":true,"ClassificationFilterEnabled":true,"ClientRoutingEnabled":true,"EnableYammerGroupOption":true,"EnableFadeMessage":false,"EnableDomainBasedOwaConnectorList":false,"EnableDomainBasedTeamsConnectorList":false,"DevPortalSPAEnabled":true,"ShowHomeNavigationButtonOnConfigurationPage":false,"DisableConnectToO365InlineDeleteFeedbackPage":true},"status":500,"clientType":"SkypeSpaces","connectorType":"0b73c39a-db1d-43eb-81bd-3813bef33713","name":"handleMessageError"}
Thanks for any guidance you might have. If I can get in touch with someone from Microsoft privately, I'd be happy to provide the <redacted> information.

Answer 1

This issue is fixed by adding the content url in valid domains list in the Connector Developer Dashboard.

Answer 2

As recommended above: This issue is fixed by adding the content url in a valid domains list in the Connector Developer Dashboard.
This helped me understand the direction of the problem.
But my accidental mistake was due to the lack of the prefix https://
Be sure to add https:// prefix to your domain