Some Service Desk functionalities not working as expected when Jira is connected to an LDAP server that's temporarily not reachable

Issue Summary

When Jira is configured and LDAP directory ranked first in the directory list, various Service Desk functionalities fail to work whenever the LDAP directory is temporarily unavailable and throw a confusing error "Signup is not currently available".

Some examples of functionalities that are impacted are listed below:

• Incoming Mails are rejected from new customers, even if the Service Desk portal is configured with "Public Signup" enabled
• New customers can't signup on the customer portal and no message is thrown in the UI (already tracked in the bug: JSDSERVER-5791)
• New customers can't be created by using the Service Desk API and an incorrect message is returned

Environment

Reproduced in JSD 4.4.2, 4.13.1, but this issue was probably there in older JSD versions (3.x).

Steps to reproduce

• Install a new Jira application
• Create a new Service Desk project
• Configure the Service Desk project with Public signup enabled
• Configure a mail handler in the Service Desk project via Project Settings > Email Requests
• Configure an LDAP directory in ⚙ > User Management > User Directories, with Read/Write
• Rank this LDAP Directory above Jira's Internal Directory
• Make the LDAP server temporarily unavailable from Jira, for example by stop the LDAP Server
• Try each the 3 actions below
• Action 1
  • Send an email to the Service Desk Mail handler from an email address which is not associated to any Jira user
• Action 2
  • Open the Service Desk customer portal (and don't sign in yet)
  • Click the link Sign up for an account
  • Try to create an account using an email address which is not associated to any Jira user
  • Click the sign up button
• Action 3
  • Open Postman or any other API tool
  • Try to create a new customer using an email address which is not associated to any Jira user

    POST: <JIRA_BASE_URL>/rest/servicedeskapi/customer
    body:
    {
        "email": "test@test.com",
        "fullName": "test@test.com"
    }
    

Actual Results

Action 1

The incoming mail is rejected by the Mail handler and therefore lost, even though the Project is configured with Public Sign up:

Signup is not currently available

Action 2

Nothing happens when clicking the Sign up button, and no message is thrown in the UI. When using the Browser Dev Tool to analyze the HTTP response, the following message is returned with error code 400, even though the Project is configured with Public Sign up:

Signup is not currently available

Action 3

The API returns the following message with error code 400, even though the Project is configured with Public Sign up:

Signup is not currently available

Expected results

Action 1

• The error message should be changed to something like:

  Failed to create a new account from the email address due to the LDAP server being unavailable

• Ideally, the email should be temporarily labeled in the JSD Database as "temporary failure", and the JSD Mail handler should try to process the same email a few more times before completely dropping it

Action 2

The UI should display a clear message indicating why the sign up button is not working, something like:

The signup functionality is temporary unavailable. Please try again later

Action 3

A different message should be returned from the API call, something like:

Failed to create a new account from the email address due to the LDAP server being unavailable