"Failed to send Webhook...Content type text/html; charset=utf-8 is not currently supported" error when sending webhook to Slack

Products

• VCF Operations/Automation (formerly VMware Aria Suite)
• VCF Operations

Issue/Introduction

• Integrating Operations with Slack using the Slack plugin works well, but the lack of options to customize the alerts that Operations sends to Slack requires the use of webhooks instead.
• When using Webhook, the following error message is seen in Operations:

Failed to post to the server.[Failed to send Webhook: java.lang.RuntimeException: java.lang.RuntimeException: Content type text/html; charset=utf-8 is not currently supported.]

Environment

Aria Operations 8.x

VCF Operations 9.x

Cause

The webhook Outbound Notification is configured to use OAuth Authentication instead of No Credential.

Resolution

Modify the Outbound Settings for the webhook

1. Log in to Operations UI and navigate to Infrastructure Operations > Configurations > Outbound Settings
2. Click the vertical three dots next to the webhook outbound method and select Edit
3. Set the Credential type field to No Credential
   
   Note: Clicking TEST will result in an error "Test was not successful: Failed to post to the server" due to the default payload that is used for testing webhook outbound methods. The default payload is not configured with the fields that Slack requires. This is expected behavior.
   
4. Click SAVE
5. Click YES in the warning dialog that says "Failed to post to the server. Proceed anyway?"

Additional Information

For more details regarding configuring payload templates in a manner that Slack expects, review the Slack documentation.

• Sending messages using incoming webhooks