diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -2951,7 +2951,7 @@
 
     See :hg:`help revisions` for more about specifying revisions.
 
-    Returns 0 on successful completion.
+    Returns 0 on successful completion, 1 if there are unresolved files.
     '''
     with repo.wlock():
         return _dograft(ui, repo, *revs, **opts)
@@ -3212,10 +3212,9 @@
                 statedata[b'nodes'] = nodes
                 stateversion = 1
                 graftstate.save(stateversion, statedata)
-                hint = _(b"use 'hg resolve' and 'hg graft --continue'")
-                raise error.Abort(
-                    _(b"unresolved conflicts, can't continue"), hint=hint
-                )
+                ui.error(_(b"abort: unresolved conflicts, can't continue\n"))
+                ui.error(_(b"(use 'hg resolve' and 'hg graft --continue')\n"))
+                return 1
         else:
             cont = False
 
diff --git a/tests/test-bisect.t b/tests/test-bisect.t
--- a/tests/test-bisect.t
+++ b/tests/test-bisect.t
@@ -564,7 +564,7 @@
   warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
   $ hg bisect --reset
   $ hg up -C .
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
diff --git a/tests/test-copies-unrelated.t b/tests/test-copies-unrelated.t
--- a/tests/test-copies-unrelated.t
+++ b/tests/test-copies-unrelated.t
@@ -109,7 +109,7 @@
   What do you want to do? u
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
 Add x, remove it, then add it back, then rename x to y. Similar to the case
 above, but here the break in history is before the rename.
@@ -193,7 +193,7 @@
   What do you want to do? u
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 #endif
   $ hg co -qC 2
 BROKEN: This should succeed and merge the changes from x into y
@@ -204,7 +204,7 @@
   What do you want to do? u
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
 Add x, remove it, then add it back, rename x to y from the first commit.
 Similar to the case above, but here the break in history is parallel to the
@@ -278,7 +278,7 @@
   What do you want to do? u
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
 Add x on two branches, then rename x to y on one side. Similar to the case
 above, but here the break in history is via the base commit.
@@ -361,7 +361,7 @@
   What do you want to do? u
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 #endif
   $ hg co -qC 2
 BROKEN: This should succeed and merge the changes from x into y
@@ -372,7 +372,7 @@
   What do you want to do? u
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
 Copies via null revision (there shouldn't be any)
   $ newrepo
diff --git a/tests/test-graft-interrupted.t b/tests/test-graft-interrupted.t
--- a/tests/test-graft-interrupted.t
+++ b/tests/test-graft-interrupted.t
@@ -32,7 +32,7 @@
   warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
 Writing the nodes in old format to graftstate
 
@@ -91,7 +91,7 @@
   warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
   $ echo wat > b
   $ hg resolve -m
@@ -141,7 +141,7 @@
   warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
   $ echo foobar > b
   $ hg resolve -m
@@ -180,7 +180,7 @@
   warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
   $ echo foobar > b
   $ hg resolve -m
@@ -246,7 +246,7 @@
   warning: conflicts while merging d! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
   $ hg graft --stop --continue
   abort: cannot use '--continue' and '--stop' together
@@ -283,7 +283,7 @@
   warning: conflicts while merging d! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
   $ hg graft --stop
   stopped the interrupted graft
@@ -352,7 +352,7 @@
   warning: conflicts while merging c! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
   $ hg graft --continue --abort
   abort: cannot use '--continue' and '--abort' together
@@ -399,7 +399,7 @@
   warning: conflicts while merging c! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
   $ hg abort
   graft aborted
@@ -426,7 +426,7 @@
   warning: conflicts while merging c! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
   $ hg log -GT "{rev}:{node|short} {desc}"
   @  6:6ec71c037d94 added x
@@ -488,7 +488,7 @@
   warning: conflicts while merging c! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
   $ cd ..
   $ hg init pullrepo
@@ -609,7 +609,7 @@
   warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
 Resolve conflict:
   $ echo A>a
@@ -648,7 +648,7 @@
   warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
 Resolve conflict:
   $ echo A>a
@@ -688,7 +688,7 @@
   warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
   $ echo A>a
   $ hg resolve --mark
diff --git a/tests/test-graft.t b/tests/test-graft.t
--- a/tests/test-graft.t
+++ b/tests/test-graft.t
@@ -260,7 +260,7 @@
   warning: conflicts while merging e! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
 Summary should mention graft:
 
@@ -317,7 +317,7 @@
   warning: conflicts while merging e! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
 
 Continue without resolve should fail:
 
@@ -511,7 +511,7 @@
   grafting 1:5d205f8b35b6 "1"
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
   $ hg resolve --all
   merging a
   warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
@@ -551,7 +551,7 @@
   grafting 2:5c095ad7e90f "2"
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
   $ hg resolve --all
   merging a and b to b
   (no more unresolved files)
@@ -839,7 +839,7 @@
   grafting 24:2e7ea477be26 "24"
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
   $ hg resolve --all
   merging a
   warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
diff --git a/tests/test-issue1175.t b/tests/test-issue1175.t
--- a/tests/test-issue1175.t
+++ b/tests/test-issue1175.t
@@ -74,7 +74,7 @@
   warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
-  [255]
+  [1]
   $ echo a > b
   $ echo b3 >> b
   $ hg resolve --mark b