Connection between JIRA Server and BitBucket Cloud fails

[Jason Rider]

it seems as of late, that the DVCS connection between our JIRA server and Bitbucket cloud is failing.

Nothing has changed on our servers or anything.

But going to the JIRA Admin > Applications > DVCS Accounts.  

It says "Sync Failed" under Last Activity, and nexrt to the Bitbucket Team name, it says Invalid Credentials, please reset OAuth settings.

I verified the OAuth Key and Secret, it hasn't changed.  But I try to regenerate access token, (the prompt says the Authorizing Account is invalid, please regenerate access token), and it gives this error:

Error!
Cannot proceed authentication, check OAuth credentials for account <Bitbucket team>

I tried creating a new OAuth Key/Secret, but still get the same error.  

I checked atlassian-jira.log

This is the latest entry:

2016-05-26 14:32:13,251 StreamsCompletionService::thread-2726 WARN <myfirstname.lastname>872x283200x1 1xsdnd8 192.168.1.115,0:0:0:0:0:0:0:1 /plugins/servlet/streams [c.a.j.p.d.s.b.clientlibrary.request.BaseRemoteRequestor] Failed to properly execute request [GET https://bitbucket.org/api/1.0/users/<my bitbucket username>],

There are a lot of entries similar of it trying to execute requests to the BB API.

Running a similar command:

wget -p https://bitbucket.org/api/1.0/repositories/<team>/framework/branches-tags -O /dev/null

results in:

401 UNAUTHORIZED  Username/Password Authentication Failed

[Yogesh Mude[Jira]]

Hi,

Its  authentication error so please provide correct Username and Password.

[Jason Rider]

Username and Password to where?  There is no place to input a username and password

I have verified the Key and Secret in JIRA > DVCS Accounts > Reset OAuth Settings

The Secret and Key are correct from the corresponding BB Team OAuth Settings

[Jason Rider]

I have tried deleting the Account from JIRA to re-add the account, yet, get this error:

Error!
The authentication with Bitbucket has failed. Please check your OAuth settings.

I check atlassian-jira.log, I see no error messages at all.

[rossdd-atl]

I encountered this same issue and was able to resolve it by editing the Consumer it Bitbucket to be a Private Consumer. This was not mentioned in the documentation I read at https://confluence.atlassian.com/bitbucket/connect-bitbucket-cloud-to-jira-software-server-814208991.html