--- a/hgext/configwizard/__init__.py
+++ b/hgext/configwizard/__init__.py
@@ -42,20 +42,25 @@ The wizard makes no changes without your
 To begin, press the enter/return key.
 '''.lstrip()
 
 MINIMUM_SUPPORTED_VERSION = (3, 5, 0)
 
 OLDEST_NON_LEGACY_VERSION = (3, 7, 3)
 
 VERSION_TOO_OLD = '''
-Your version of Mercurial is too old to run `hg configwizard`.
+Your version of Mercurial (%d.%d) is too old to run `hg configwizard`.
 
 Mozilla's Mercurial support policy is to support at most the past
 1 year of Mercurial releases (or 4 major Mercurial releases).
+
+Please upgrade to Mercurial %d.%d or newer and try again.
+
+See https://mozilla-version-control-tools.readthedocs.io/en/latest/hgmozilla/installing.html
+for Mozilla-tailored instructions for install Mercurial.
 '''.lstrip()
 
 LEGACY_MERCURIAL_MESSAGE = '''
 You are running an out of date Mercurial client (%s).
 
 For a faster and better Mercurial experience, we HIGHLY recommend you
 upgrade.
 
@@ -292,17 +297,20 @@ def configwizard(ui, repo, statedir=None
     """Ensure your Mercurial configuration is up to date."""
     runsteps = set(wizardsteps)
     if ui.hasconfig('configwizard', 'steps'):
         runsteps = set(ui.configlist('configwizard', 'steps'))
 
     hgversion = util.versiontuple(n=3)
 
     if hgversion < MINIMUM_SUPPORTED_VERSION:
-        ui.warn(VERSION_TOO_OLD)
+        ui.warn(VERSION_TOO_OLD % (
+            hgversion[0], hgversion[1],
+            MINIMUM_SUPPORTED_VERSION[0], MINIMUM_SUPPORTED_VERSION[1],
+        ))
         raise error.Abort('upgrade Mercurial then run again')
 
     uiprompt(ui, INITIAL_MESSAGE, default='<RETURN>')
 
     configpaths = [p for p in scmutil.userrcpath() if os.path.exists(p)]
     path = configpaths[0] if configpaths else scmutil.userrcpath()[0]
     cw = configobjwrapper(path)
 

--- a/hgext/configwizard/tests/test-legacy-version.t
+++ b/hgext/configwizard/tests/test-legacy-version.t
@@ -76,14 +76,19 @@ Old version will print legacy message an
 Too old version will fail outright
 
   $ rm fakeversion.pyc
   $ cat >> fakeversion.py << EOF
   > util.version = lambda: '3.4.2'
   > EOF
 
   $ hg $FAKEVERSION --config configwizard.steps=hgversion configwizard
-  Your version of Mercurial is too old to run `hg configwizard`.
+  Your version of Mercurial (3.4) is too old to run `hg configwizard`.
   
   Mozilla's Mercurial support policy is to support at most the past
   1 year of Mercurial releases (or 4 major Mercurial releases).
+  
+  Please upgrade to Mercurial 3.5 or newer and try again.
+  
+  See https://mozilla-version-control-tools.readthedocs.io/en/latest/hgmozilla/installing.html
+  for Mozilla-tailored instructions for install Mercurial.
   abort: upgrade Mercurial then run again
   [255]