"trac-admin [project base] upgrade" fails due to "TypeError: environment_needs_upgrade() takes exactly 2 arguments (1 given)"

[krichter@…]

After installing 1.3.1dev 1.1.5 over ​a1caf58 and restarting the tracd standalone instance, the web frontend displays

Error

TracError: The Trac Environment needs to be upgraded.

Run "trac-admin /var/lib/trac/sci-d-wiki upgrade"

and running sudo trac-admin /var/lib/trac/sci-d-wiki upgrade fails due to

The upgrade failed. Please fix the issue and try again.

TypeError: environment_needs_upgrade() takes exactly 2 arguments (1 given)

/var/lib/trac/sci-d-wiki/log/trac.log reveals

2016-10-23 13:51:31,806 Trac[api] INFO: Need to upgrade database_version from 40 to 42
2016-10-23 13:51:31,806 Trac[env] WARNING: Component <Component trac.env.EnvironmentSetup> requires environment upgrade
2016-10-23 13:51:31,807 Trac[api] INFO: Need to upgrade database_version from 40 to 42
2016-10-23 13:51:31,807 Trac[env] WARNING: Component <Component trac.env.EnvironmentSetup> requires environment upgrade
2016-10-23 13:51:31,807 Trac[api] INFO: Need to upgrade database_version from 40 to 42
2016-10-23 13:51:31,809 Trac[console] ERROR: Exception in trac-admin command: u'upgrade'
Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/trac/admin/console.py", line 112, in onecmd
    rv = cmd.Cmd.onecmd(self, line) or 0
  File "/usr/lib/python2.7/cmd.py", line 220, in onecmd
    return self.default(line)
  File "build/bdist.linux-x86_64/egg/trac/admin/console.py", line 291, in default
    return self.cmd_mgr.execute_command(*args)
  File "build/bdist.linux-x86_64/egg/trac/admin/api.py", line 127, in execute_command
    return f(*fargs)
  File "build/bdist.linux-x86_64/egg/trac/env.py", line 945, in _do_upgrade
    self.env.upgrade(backup=no_backup is None)
  File "build/bdist.linux-x86_64/egg/trac/env.py", line 691, in upgrade
    if participant.environment_needs_upgrade():
TypeError: environment_needs_upgrade() takes exactly 2 arguments (1 given)

[Jun Omae]

I guess your installed plugin(s) lead it. Please re-try after plugins are disabled/uninstalled.