diff --git a/mercurial/upgrade_utils/actions.py b/mercurial/upgrade_utils/actions.py
--- a/mercurial/upgrade_utils/actions.py
+++ b/mercurial/upgrade_utils/actions.py
@@ -325,27 +325,6 @@
 
 
 @registerformatvariant
-class sidedata(requirementformatvariant):
-    name = b'sidedata'
-
-    _requirement = requirements.REVLOGV2_REQUIREMENT
-
-    default = False
-
-    description = _(
-        b'Allows storage of extra data alongside a revision, '
-        b'unlocking various caching options.'
-    )
-
-    upgrademessage = _(b'Allows storage of extra data alongside a revision.')
-
-    @classmethod
-    def fromrepo(cls, repo):
-        assert cls._requirement is not None
-        return cls._requirement in repo.requirements
-
-
-@registerformatvariant
 class persistentnodemap(requirementformatvariant):
     name = b'persistent-nodemap'
 
diff --git a/tests/test-copies-chain-merge.t b/tests/test-copies-chain-merge.t
--- a/tests/test-copies-chain-merge.t
+++ b/tests/test-copies-chain-merge.t
@@ -1466,7 +1466,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no    yes      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no    yes      no
   revlog-v2:           no    yes      no
@@ -1506,7 +1505,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no    yes      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no    yes      no
   revlog-v2:           no    yes      no
diff --git a/tests/test-copies-in-changeset.t b/tests/test-copies-in-changeset.t
--- a/tests/test-copies-in-changeset.t
+++ b/tests/test-copies-in-changeset.t
@@ -39,7 +39,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:           yes    yes      no
   persistent-nodemap:  no     no      no
   copies-sdc:         yes    yes      no
   revlog-v2:          yes    yes      no
@@ -54,7 +53,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
@@ -426,7 +424,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:           yes    yes      no
   persistent-nodemap:  no     no      no
   copies-sdc:         yes    yes      no
   revlog-v2:          yes    yes      no
@@ -453,7 +450,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:           yes    yes      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:          yes    yes      no
@@ -482,7 +478,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:           yes    yes      no
   persistent-nodemap:  no     no      no
   copies-sdc:         yes    yes      no
   revlog-v2:          yes    yes      no
diff --git a/tests/test-persistent-nodemap.t b/tests/test-persistent-nodemap.t
--- a/tests/test-persistent-nodemap.t
+++ b/tests/test-persistent-nodemap.t
@@ -56,7 +56,6 @@
   generaldelta:       yes
   share-safe:          no
   sparserevlog:       yes
-  sidedata:            no
   persistent-nodemap: yes
   copies-sdc:          no
   revlog-v2:           no
@@ -576,7 +575,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no     no      no
   persistent-nodemap: yes     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
@@ -622,7 +620,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no     no      no
   persistent-nodemap:  no    yes      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
diff --git a/tests/test-sidedata.t b/tests/test-sidedata.t
--- a/tests/test-sidedata.t
+++ b/tests/test-sidedata.t
@@ -56,7 +56,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
@@ -70,7 +69,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no    yes      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no    yes      no
@@ -90,7 +88,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:           yes     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:          yes     no      no
@@ -104,7 +101,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:           yes     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:          yes     no      no
diff --git a/tests/test-upgrade-repo.t b/tests/test-upgrade-repo.t
--- a/tests/test-upgrade-repo.t
+++ b/tests/test-upgrade-repo.t
@@ -58,7 +58,6 @@
   generaldelta:       yes
   share-safe:          no
   sparserevlog:       yes
-  sidedata:            no
   persistent-nodemap:  no
   copies-sdc:          no
   revlog-v2:           no
@@ -72,7 +71,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
@@ -86,7 +84,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
@@ -100,7 +97,6 @@
   [formatvariant.name.uptodate|generaldelta:      ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]
   [formatvariant.name.uptodate|share-safe:        ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.uptodate|sparserevlog:      ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]
-  [formatvariant.name.uptodate|sidedata:          ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.uptodate|persistent-nodemap:][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.uptodate|copies-sdc:        ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.uptodate|revlog-v2:         ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
@@ -142,12 +138,6 @@
    {
     "config": false,
     "default": false,
-    "name": "sidedata",
-    "repo": false
-   },
-   {
-    "config": false,
-    "default": false,
     "name": "persistent-nodemap",
     "repo": false
    },
@@ -313,7 +303,6 @@
   generaldelta:        no
   share-safe:          no
   sparserevlog:        no
-  sidedata:            no
   persistent-nodemap:  no
   copies-sdc:          no
   revlog-v2:           no
@@ -327,7 +316,6 @@
   generaldelta:        no    yes     yes
   share-safe:          no     no      no
   sparserevlog:        no    yes     yes
-  sidedata:            no     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
@@ -341,7 +329,6 @@
   generaldelta:        no     no     yes
   share-safe:          no     no      no
   sparserevlog:        no     no     yes
-  sidedata:            no     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
@@ -355,7 +342,6 @@
   [formatvariant.name.mismatchdefault|generaldelta:      ][formatvariant.repo.mismatchdefault|  no][formatvariant.config.special|     no][formatvariant.default|     yes]
   [formatvariant.name.uptodate|share-safe:        ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.mismatchdefault|sparserevlog:      ][formatvariant.repo.mismatchdefault|  no][formatvariant.config.special|     no][formatvariant.default|     yes]
-  [formatvariant.name.uptodate|sidedata:          ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.uptodate|persistent-nodemap:][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.uptodate|copies-sdc:        ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.uptodate|revlog-v2:         ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
@@ -1299,7 +1285,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
@@ -1336,7 +1321,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
@@ -1376,7 +1360,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
@@ -1421,7 +1404,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:           yes     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:          yes     no      no
@@ -1466,7 +1448,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:            no     no      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:           no     no      no
@@ -1511,7 +1492,6 @@
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
   sparserevlog:       yes    yes     yes
-  sidedata:           yes    yes      no
   persistent-nodemap:  no     no      no
   copies-sdc:          no     no      no
   revlog-v2:          yes    yes      no