Problem

Users see a 'Can't load the editor' error in Firefox when attempting to edit a page, and Confluence Data Center 6.9 (or later) is running in an IPv6 environment. 

Cause

This problem is caused by a raw IPv6 address being used for the Synchrony URL in the Synchrony startup script, for example:

# URL that the browser uses to contact Synchrony 
#SYNCHRONY_URL="http://[1234:dal:698:7d01:20ce:53f8:bcf0:ab1d]:8091/synchrony"

and in Confluence's bin/setenv file. 

#CATALINA_OPTS="-Dsynchrony.service.url=http://[1234:dal:698:7d01:20ce:53f8:bcf0:ab1c]:8091/synchrony/v1 ${CATALINA_OPTS}"

The examples above are for Linux, but the same applies in Windows environments. 

Workaround

To avoid this problem, you will need to specify the DNS hostname for Synchrony, instead of using the raw IPv6 address. 

1. Stop Confluence and Synchrony. 

2. Edit the start-synchrony.sh / start-synchrony.bat script, and specify the DNS hostname for Synchrony. Here's an example:

   Linux

   # URL that the browser uses to contact Synchrony
   SYNCHRONY_URL="http://confluence-ipv6.examplesite.com:8091/synchrony"

   Windows

   rem URL that the browser uses to contact Synchrony
   set SYNCHRONY_URL=http://confluence-ipv6.examplesite.com:8091/synchrony

3.  Edit <confluence-install-directory>/bin/setenv.sh or setenv.bat and update the synchrony.service.url system property:

   Linux

   CATALINA_OPTS="-Dsynchrony.service.url=http://confluence-ipv6.examplesite.com:8091/synchrony/v1 ${CATALINA_OPTS}"

   Windows

   set CATALINA_OPTS=http://confluence-ipv6.examplesite.com:8091/synchrony/v1 %CATALINA_OPTS%

4. Restart Synchrony, then restart Confluence.