diff --git a/mercurial/rewriteutil.py b/mercurial/rewriteutil.py
--- a/mercurial/rewriteutil.py
+++ b/mercurial/rewriteutil.py
@@ -54,7 +54,10 @@ def precheck(repo, revs, action=b'rewrit
 
     newunstable = disallowednewunstable(repo, revs)
     if newunstable:
-        raise error.InputError(_(b"cannot %s changeset with children") % action)
+        hint = _(b"see 'hg help evolution.instability'")
+        raise error.InputError(
+            _(b"cannot %s changeset with children") % action, hint=hint
+        )
 
 
 def disallowednewunstable(repo, revs):
diff --git a/tests/test-amend.t b/tests/test-amend.t
--- a/tests/test-amend.t
+++ b/tests/test-amend.t
@@ -197,6 +197,7 @@ Amend in the middle of a stack
   $ echo 2 >> B
   $ hg amend
   abort: cannot amend changeset with children
+  (see 'hg help evolution.instability')
   [10]
 
 #if obsstore-on
diff --git a/tests/test-branch-change.t b/tests/test-branch-change.t
--- a/tests/test-branch-change.t
+++ b/tests/test-branch-change.t
@@ -58,6 +58,7 @@ Change in middle of the stack (linear co
 
   $ hg branch -r 1::3 foo
   abort: cannot change branch of changeset with children
+  (see 'hg help evolution.instability')
   [10]
 
 Change with dirty working directory
@@ -129,6 +130,7 @@ Changing on a branch head which is not t
 
   $ hg branch -r 2 stable
   abort: cannot change branch of changeset with children
+  (see 'hg help evolution.instability')
   [10]
 
 Enabling the allowunstable config and trying to change branch on a branch head
diff --git a/tests/test-fix.t b/tests/test-fix.t
--- a/tests/test-fix.t
+++ b/tests/test-fix.t
@@ -1173,6 +1173,7 @@ an orphan. We must respect experimental.
   $ hg commit -m "second"
   $ hg --config experimental.evolution.allowunstable=False fix -r '.^'
   abort: cannot fix changeset with children
+  (see 'hg help evolution.instability')
   [10]
   $ hg fix -r '.^'
   1 new orphan changesets
diff --git a/tests/test-rebase-collapse.t b/tests/test-rebase-collapse.t
--- a/tests/test-rebase-collapse.t
+++ b/tests/test-rebase-collapse.t
@@ -550,7 +550,7 @@ Test collapsing a middle revision in-pla
   
   $ hg rebase --collapse -r 1 -d 0
   abort: cannot rebase changeset with children
-  (use --keep to keep original changesets)
+  (see 'hg help evolution.instability')
   [10]
 
 Test collapsing in place
diff --git a/tests/test-rebase-scenario-global.t b/tests/test-rebase-scenario-global.t
--- a/tests/test-rebase-scenario-global.t
+++ b/tests/test-rebase-scenario-global.t
@@ -453,7 +453,7 @@ Source on have two descendant heads but 
   $ cd ah1
   $ hg rebase -r '2::8' -d 1
   abort: cannot rebase changeset with children
-  (use --keep to keep original changesets)
+  (see 'hg help evolution.instability')
   [10]
   $ hg rebase -r '2::8' -d 1 -k
   rebasing 2:c9e50f6cdc55 "C"
@@ -499,7 +499,7 @@ Base on have one descendant heads we ask
   $ cd ah2
   $ hg rebase -r '3::8' -d 1
   abort: cannot rebase changeset with children
-  (use --keep to keep original changesets)
+  (see 'hg help evolution.instability')
   [10]
   $ hg rebase -r '3::8' -d 1 --keep
   rebasing 3:ffd453c31098 "D"
@@ -542,7 +542,7 @@ rebase subset
   $ cd ah3
   $ hg rebase -r '3::7' -d 1
   abort: cannot rebase changeset with children
-  (use --keep to keep original changesets)
+  (see 'hg help evolution.instability')
   [10]
   $ hg rebase -r '3::7' -d 1 --keep
   rebasing 3:ffd453c31098 "D"
@@ -582,7 +582,7 @@ rebase subset with multiple head
   $ cd ah4
   $ hg rebase -r '3::(7+5)' -d 1
   abort: cannot rebase changeset with children
-  (use --keep to keep original changesets)
+  (see 'hg help evolution.instability')
   [10]
   $ hg rebase -r '3::(7+5)' -d 1 --keep
   rebasing 3:ffd453c31098 "D"
diff --git a/tests/test-split.t b/tests/test-split.t
--- a/tests/test-split.t
+++ b/tests/test-split.t
@@ -467,6 +467,7 @@ Split a non-head without rebase
 #if obsstore-off
   $ runsplit -r 1 --no-rebase
   abort: cannot split changeset with children
+  (see 'hg help evolution.instability')
   [10]
 #else
   $ runsplit -r 1 --no-rebase >/dev/null
@@ -518,6 +519,7 @@ Split a non-head with obsoleted descenda
   $ rm .hg/localtags
   $ hg split $B --config experimental.evolution=createmarkers
   abort: cannot split changeset with children
+  (see 'hg help evolution.instability')
   [10]
   $ cat > $TESTTMP/messages <<EOF
   > Split B
diff --git a/tests/test-unamend.t b/tests/test-unamend.t
--- a/tests/test-unamend.t
+++ b/tests/test-unamend.t
@@ -284,6 +284,7 @@ Unamending in middle of a stack
 
   $ hg --config experimental.evolution=createmarkers unamend
   abort: cannot unamend changeset with children
+  (see 'hg help evolution.instability')
   [10]
 
   $ hg unamend