diff --git a/main.py b/main.py
index bafa64df..9c62722f 100755
--- a/main.py
+++ b/main.py
@@ -566,9 +566,11 @@ repo: error:
         sys.exit(1)
 
     if exp > ver:
-        logger.warn("\n... A new version of repo (%s) is available.", exp_str)
+        logger.warning(
+            "\n... A new version of repo (%s) is available.", exp_str
+        )
         if os.access(repo_path, os.W_OK):
-            logger.warn(
+            logger.warning(
                 """\
 ... You should upgrade soon:
     cp %s %s
@@ -577,7 +579,7 @@ repo: error:
                 repo_path,
             )
         else:
-            logger.warn(
+            logger.warning(
                 """\
 ... New version is available at: %s
 ... The launcher is run from: %s
diff --git a/project.py b/project.py
index 642c123f..80c20add 100644
--- a/project.py
+++ b/project.py
@@ -1262,7 +1262,7 @@ class Project(object):
             try:
                 platform_utils.remove(tarpath)
             except OSError as e:
-                logger.warn("warn: Cannot remove archive %s: %s", tarpath, e)
+                logger.warning("warn: Cannot remove archive %s: %s", tarpath, e)
             self._CopyAndLinkFiles()
             return SyncNetworkHalfResult(True)
 
@@ -1759,7 +1759,7 @@ class Project(object):
         """
         if self.IsDirty():
             if force:
-                logger.warn(
+                logger.warning(
                     "warning: %s: Removing dirty project: uncommitted changes "
                     "lost.",
                     self.RelPath(local=False),
@@ -3038,7 +3038,7 @@ class Project(object):
                 # hardlink below.
                 if not filecmp.cmp(stock_hook, dst, shallow=False):
                     if not quiet:
-                        logger.warn(
+                        logger.warning(
                             "warn: %s: Not replacing locally modified %s hook",
                             self.RelPath(local=False),
                             name,
@@ -4336,7 +4336,7 @@ class ManifestProject(MetaProject):
             self.config.SetBoolean("repo.worktree", worktree)
             if is_new:
                 self.use_git_worktrees = True
-            logger.warn("warning: --worktree is experimental!")
+            logger.warning("warning: --worktree is experimental!")
 
         if archive:
             if is_new:
@@ -4400,7 +4400,7 @@ class ManifestProject(MetaProject):
 
             self.config.SetBoolean("repo.git-lfs", git_lfs)
             if not is_new:
-                logger.warn(
+                logger.warning(
                     "warning: Changing --git-lfs settings will only affect new "
                     "project checkouts.\n"
                     "         Existing projects will require manual updates.\n"
@@ -4512,7 +4512,7 @@ class ManifestProject(MetaProject):
                 submanifest = ""
                 if self.manifest.path_prefix:
                     submanifest = f"for {self.manifest.path_prefix} "
-                logger.warn(
+                logger.warning(
                     "warning: git update of superproject %s failed, "
                     "repo sync will not use superproject to fetch source; "
                     "while this error is not fatal, and you can continue to "
diff --git a/subcmds/cherry_pick.py b/subcmds/cherry_pick.py
index f9ae3e32..3d219333 100644
--- a/subcmds/cherry_pick.py
+++ b/subcmds/cherry_pick.py
@@ -86,7 +86,7 @@ change id will be added.
             p.Wait()
         except GitError as e:
             logger.error(e)
-            logger.warn(
+            logger.warning(
                 "NOTE: When committing (please see above) and editing the "
                 "commit message, please remove the old Change-Id-line and "
                 "add:\n%s",
diff --git a/subcmds/manifest.py b/subcmds/manifest.py
index 101240d1..bb6dc930 100644
--- a/subcmds/manifest.py
+++ b/subcmds/manifest.py
@@ -136,7 +136,7 @@ to indicate the remote ref to push changes to via 'repo upload'.
             manifest.SetUseLocalManifests(not opt.ignore_local_manifests)
 
             if opt.json:
-                logger.warn("warning: --json is experimental!")
+                logger.warning("warning: --json is experimental!")
                 doc = manifest.ToDict(
                     peg_rev=opt.peg_rev,
                     peg_rev_upstream=opt.peg_rev_upstream,
@@ -163,13 +163,13 @@ to indicate the remote ref to push changes to via 'repo upload'.
             if output_file != "-":
                 fd.close()
                 if manifest.path_prefix:
-                    logger.warn(
+                    logger.warning(
                         "Saved %s submanifest to %s",
                         manifest.path_prefix,
                         output_file,
                     )
                 else:
-                    logger.warn("Saved manifest to %s", output_file)
+                    logger.warning("Saved manifest to %s", output_file)
 
     def ValidateOptions(self, opt, args):
         if args:
diff --git a/subcmds/rebase.py b/subcmds/rebase.py
index 439557c2..db1b387c 100644
--- a/subcmds/rebase.py
+++ b/subcmds/rebase.py
@@ -113,7 +113,7 @@ branch but need to incorporate new upstream changes "underneath" them.
             )
 
             if len(args) == 1:
-                logger.warn(
+                logger.warning(
                     "note: project %s is mapped to more than one path", args[0]
                 )
 
diff --git a/subcmds/sync.py b/subcmds/sync.py
index 85428b18..e1f7d019 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -1877,7 +1877,7 @@ def _PostRepoUpgrade(manifest, quiet=False):
 
 def _PostRepoFetch(rp, repo_verify=True, verbose=False):
     if rp.HasChanges:
-        logger.warn("info: A new version of repo is available")
+        logger.warning("info: A new version of repo is available")
         wrapper = Wrapper()
         try:
             rev = rp.bare_git.describe(rp.GetRevisionId())
diff --git a/subcmds/upload.py b/subcmds/upload.py
index 618a10e1..4bcdfaf9 100644
--- a/subcmds/upload.py
+++ b/subcmds/upload.py
@@ -72,16 +72,16 @@ def _VerifyPendingCommits(branches: List[ReviewableBranch]) -> bool:
     # If any branch has many commits, prompt the user.
     if many_commits:
         if len(branches) > 1:
-            logger.warn(
+            logger.warning(
                 "ATTENTION: One or more branches has an unusually high number "
                 "of commits."
             )
         else:
-            logger.warn(
+            logger.warning(
                 "ATTENTION: You are uploading an unusually high number of "
                 "commits."
             )
-        logger.warn(
+        logger.warning(
             "YOU PROBABLY DO NOT MEAN TO DO THIS. (Did you rebase across "
             "branches?)"
         )