Selecting numerous Advanced Roadmaps Plans results in a connection error

Issue Summary

Selecting a great number of Advanced Roadmaps (AR) Plans while creating a new migration plan results in a connection issue.

Steps to Reproduce

Precondition: Have numerous (100+) AR Plans.

1. From the Migration Dashboard, click Create new migration.
2. Populate the data for the migration destination site.
3. In the Choose migration options screen, scope all Advanced Roadmaps plans.

Expected Results

The AR Plans would be scoped in the migration without errors.

Actual Results

A connection issue "Error communicating with server" is raised after scoping Plans.

An HTTP 400 can be seen from the browser console and in the Catalina logs: 

HTTP 400 - Bad Request
java.lang.IllegalArgumentException: Request header is too large

The request is formed by appending all the Plan IDs with "&plansIds=xxx" in the URL path. A great number of plans will easily exceed the maxHttpHeaderSize threshold.

Workaround

To resolve this, could you please follow the below steps:

• Open the <jira-install>/conf/server.xml.
• Edit the <Connector> element and adjust the parameter to the below value, specified in bytes:

• <Connector [other attributes] maxHttpHeaderSize="16384"/>

   This will set the maximum header value to 16384 bytes.
   This change will require a restart of the application in order to take effect.