Problem

When creating a new Application Link an Error banner is displayed behind the Application Link modal. The modal does not go away until you click Cancel.

As illustrated in the screenshot:

Diagnosis

Diagnostic Steps

• To better understand why the link does not get created successfully, we can use the browser's developer tools.
  
  • See Generating HAR files and analyzing web requests for more details
• The HAR File shows us the response is 401 Unauthorized 

• With the use of Applinks Diagnostics Plugin we can further diagnose why the Application Link fails to create. In this example you'll see the echo response test is failing:

  HTTP Echo: fail
  .
  .
  .
  Request URL is inconsistent. Sent
  [http://stash."...".local/plugins/servlet/applinksDiagnostics/echo]
  Received
  [http://patlah1inf01."...".local:7990/plugins/servlet/applinksDiagnostics/echo]
  
  Echo response is inconsistent with request

  Authentication Check: warn
  Server date: Mon, 18 May 2015 01:36:19 GMT
  
  Attempting authentication of link to Stash
  
  Checking if OAuthAuthenticationProvider is
  configured
  
  OAuthAuthenticationProvider is configured for
  Stash, trying authentication
  
  Attempting to request
  http://stash.investlab.local/plugins/servlet/applinksDiagnostics/authenticate
  
  OAuthAuthenticationProvider Failed to get token
  from service provider, problem was: 'signature_invalid'
  
  Failed to connect using
  OAuthAuthenticationProvider to Stash
  

• By comparing a HAR file and results of the Application Diagnostics you'll see that there is a problem with authentication.

Cause

• One of the applications is accessed through a reverse proxy, while the other one is not. 

Workaround

• Bypass the proxy on both sides and try creating the Application Link again.

You can bypass a proxy by setting up a second connector in Tomcat to be used specifically for the application link. For more details take a look at Step 1.3 of Integrating JIRA with Apache