diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -1866,7 +1866,7 @@
     if version is None:
         raise ValueError(b'bundler does not support common obsmarker format')
     stream = obsolete.encodemarkers(markers, True, version=version)
-    return bundler.newpart(b'obsmarkers', data=stream)
+    return bundler.newpart(b'obsmarkers', data=stream, mandatory=False)
 
 
 def writebundle(
diff --git a/tests/test-obsolete-bundle-strip.t b/tests/test-obsolete-bundle-strip.t
--- a/tests/test-obsolete-bundle-strip.t
+++ b/tests/test-obsolete-bundle-strip.t
@@ -1444,3 +1444,35 @@
   # unbundling: new changesets 9ac430e15fca (1 drafts)
   # unbundling: (1 other changesets obsolete on arrival)
   # unbundling: (run 'hg update' to get a working copy)
+
+Test that obsolescence markers in bundles are ignored if unsupported
+
+  $ hg init repo-with-obs
+  $ cd repo-with-obs
+  $ hg debugbuilddag +1
+  $ hg debugobsolete `getid 0`
+  1 new obsolescence markers
+  obsoleted 1 changesets
+  $ hg bundle --config experimental.evolution.bundle-obsmarker=true --all --hidden bundle-with-obs
+  1 changesets found
+  $ cd ..
+  $ hg init repo-without-obs
+  $ cd repo-without-obs
+  $ hg --config experimental.evolution=False unbundle ../repo-with-obs/bundle-with-obs --debug
+  bundle2-input-bundle: 1 params with-transaction
+  bundle2-input-part: "changegroup" (params: 1 mandatory 1 advisory) supported
+  adding changesets
+  add changeset 1ea73414a91b
+  adding manifests
+  adding file changes
+  bundle2-input-part: total payload size 190
+  bundle2-input-part: "cache:rev-branch-cache" (advisory) supported
+  bundle2-input-part: total payload size 39
+  bundle2-input-part: "obsmarkers" (advisory) supported
+  bundle2-input-part: total payload size 50
+  ignoring obsolescence markers, feature not enabled
+  bundle2-input-bundle: 3 parts total
+  updating the branch cache
+  added 1 changesets with 0 changes to 0 files
+  new changesets 1ea73414a91b (1 drafts)
+  (run 'hg update' to get a working copy)
diff --git a/tests/test-obsolete-changeset-exchange.t b/tests/test-obsolete-changeset-exchange.t
--- a/tests/test-obsolete-changeset-exchange.t
+++ b/tests/test-obsolete-changeset-exchange.t
@@ -103,7 +103,7 @@
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       f89bcc95eba5174b1ccc3e33a82e84c96e8338ee
   cache:rev-branch-cache -- {} (mandatory: False)
-  obsmarkers -- {} (mandatory: True)
+  obsmarkers -- {} (mandatory: False)
       version: 1 (70 bytes)
       9d73aac1b2ed7d53835eaeec212ed41ea47da53a f89bcc95eba5174b1ccc3e33a82e84c96e8338ee 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
 
diff --git a/tests/test-obsolete.t b/tests/test-obsolete.t
--- a/tests/test-obsolete.t
+++ b/tests/test-obsolete.t
@@ -1632,7 +1632,7 @@
       e016b03fd86fcccc54817d120b90b751aaf367d6
       b0551702f918510f01ae838ab03a463054c67b46
   cache:rev-branch-cache -- {} (mandatory: False)
-  obsmarkers -- {} (mandatory: True)
+  obsmarkers -- {} (mandatory: False)
       version: 1 (92 bytes)
       e008cf2834908e5d6b0f792a9d4b0e2272260fb8 b0551702f918510f01ae838ab03a463054c67b46 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '8', 'operation': 'amend', 'user': 'test'}
   phase-heads -- {} (mandatory: True)