Problem

After Confluence crashes or when it is not stopped properly, you are unable to restart Synchrony.

When starting Synchrony, the following appears in the atlassian-confluence.log

2018-08-20 01:12:18,888 ERROR [Long running task: Restart Synchrony Task] [plugins.synchrony.bootstrap.DefaultSynchronyProcessManager] startup Cannot kill the running Synchrony process although the synchrony.pid file exists
 -- url: /rest/synchrony-interop/restart | referer: http://company.com:8090/admin/confluence-collaborative-editor-plugin/configure.action | traceId: 54b5b01a783we70 | userName: admin

Diagnosis

Environment

• Confluence 6+

This is related to the following issue with Confluence/Synchrony:  CONFSERVER-54876 - Getting issue details... STATUS

Cause

There is a synchrony.pid file in the confluence_install/temp/ folder that makes Confluence think that Synchrony is already running.

Resolution

Steps to resolve this:

1. Shutdown Confluence
2. Clear the plugin cache

3. Manually delete the following file:

   confluence_install/temp/synchrony.pid

4. Start Confluence
5. Go to Admin → General configuration → Collaborative editing
6. Restart Synchrony