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Community Member

No error details reported for invalid LTI configuration JSON by URL


The content by that URL is:

  "title": "Test Tool",
  "description": "My Test Tool",
  "privacy_level": "public",
  "oidc_initiation_url": "",
  "target_link_uri": "",
  "scopes": [
  "extensions": {
    "domain": "",
    "tool_id": "ace_tuition_ucat",
    "platform": "",
    "text": ""
  "public_jwk_url": ""

Now, in Canvas admin panel, I'm adding a new LTI tool and specifying its configuration by entering the URL above.

When I click on the green Save button, a generic error is reported, which is not useful at all.

When I use my developer console to inspect the request that Canvas makes, I can see the following JSON request is sent to the server:

  "tool_configuration": {
    "settings_url": ""
  "developer_key": {
    "name": "Test Tool [do not use for real testing]",
    "email": "",
    "redirect_uris": "",
    "notes": "This is for development purposes only, never use with real testing!"

... and the following response is returned:

  "errors": [
      "field": "configuration_url",
      "message": "Content type must be \"application/json\"",
      "error_code": null
  "error_report_id": "339438"

So, the error says something about configuration_url, but I have no idea where it comes from. And there is no other detail reported in the admin control panel where I'm trying to add an LTI tool. I am stuck. Please advise.

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For anyone else that comes across this question, I think the issue is that the Content-Type header being returned from was probably set to "text/html" rather than the expected "application/json".  Even if your page is returning JSON, not setting the proper Content-Type header could be causing Canvas to throw that error.