Problem

When trying to delete an Application Link in Jira, the link cannot be deleted and Jira displays a warning related to 'com.atlassian.cache.CacheException: java.lang.NullPointerException: consumer'. This will also cause the features of the Application Link to not function and the following appears in the atlassian-jira.log:

ajp-nio-127.0.0.104-8009-exec-4 WARN user 455x61414x2 1ec9rm1 192.168.1.10 /secure/RapidBoard.jspa [com.atlassian.ozymandias.SafePluginPointAccess] Unable to run plugin code because of 'com.atlassian.cache.CacheException: java.lang.NullPointerException: consumer'.

Diagnosis

Run the following query and look for a difference in the consumer_key between rows. If there is a difference between consumer_key for rows with the same token_key (excluding the username part) you're likely affected by this issue.

select * from oauthconsumertoken;
 
  id   |          created           |                    token_key                     |              token               |           token_secret           | token_type |               consumer_key
-------+----------------------------+--------------------------------------------------+----------------------------------+----------------------------------+------------+-------------------------------------------
 10309 | 2015-07-01 19:35:59.842+00 | a5f05bf0-3feb-3479-b101-d5ac9e8ea56d:user1       | XIUnPN1Qc982jufnQypngok5IBWqoIWu | FM2lRWLrOHhXLdYwJtwwFI4SO3aftiQV | ACCESS     | jira:2225f1ed-e21b-4ada-a40e-3ad49c79d7b4
 10703 | 2015-08-04 19:03:09.688+00 | a5f05bf0-3feb-3479-b101-d5ac9e8ea56d:user2       | ZWrNaIKeQTc7NlSZKTwYqlTZpfm5cEh0 | LuIBzKD6ZmF2gPXZ2CFojBKJpb0HgYlV | ACCESS     | jira:0f5f4683-0376-418e-ba8b-28b621649018
(2 rows)

So in the example above we can see the two token_key values are the same (minus the user part at the end) 

a5f05bf0-3feb-3479-b101-d5ac9e8ea56d:user1
a5f05bf0-3feb-3479-b101-d5ac9e8ea56d:user2

But the consumer_keys for the two rows differ

jira:2225f1ed-e21b-4ada-a40e-3ad49c79d7b4
jira:0f5f4683-0376-418e-ba8b-28b621649018

Cause

This is caused by a stale consumer key being used and can occur after a migration to a new instance of Jira.

Resolution

1. Stop Jira
2. Create a backup of the Jira database
3. Identify the stale (old) consumer_key from the rows returned by the SQL query ran in the diagnosis section. The stale consumer_key is the one from the row that has the oldest value in the created column.
   1. Taking the SQL query result from the example above, the stale consumer key is "jira:2225f1ed-e21b-4ada-a40e-3ad49c79d7b4" (since it has the oldest created value)

4. Run the following query to deleted the old record, after replacing <STALE_CONSUMER_KEY> with the consumer key identified in the previous step:

   delete from oauthconsumertoken where consumer_key = '<STALE_CONSUMER_KEY>';

5. Start Jira