diff --git a/tests/unit_tests_old/tests_launch/test_launch.py b/tests/unit_tests_old/tests_launch/test_launch.py
index e47df6216e5..12af3753808 100644
--- a/tests/unit_tests_old/tests_launch/test_launch.py
+++ b/tests/unit_tests_old/tests_launch/test_launch.py
@@ -38,13 +38,25 @@ def mocked_fetchable_git_repo():
     m = mock.Mock()
 
     def populate_dst_dir(dst_dir):
+        repo = mock.Mock()
+        reference = mock.Mock()
+        reference.name = "master"
+        repo.references = [reference]
+
+        def create_remote(o, r):
+            origin = mock.Mock()
+            origin.refs = {"master": mock.Mock()}
+            return origin
+
+        repo.create_remote = create_remote
+        repo.heads = {"master": mock.Mock()}
         with open(os.path.join(dst_dir, "train.py"), "w") as f:
             f.write(fixture_open("train.py").read())
         with open(os.path.join(dst_dir, "requirements.txt"), "w") as f:
             f.write(fixture_open("requirements.txt").read())
         with open(os.path.join(dst_dir, "patch.txt"), "w") as f:
             f.write("test")
-        return mock.Mock()
+        return repo
 
     m.Repo.init = mock.Mock(side_effect=populate_dst_dir)
     with mock.patch.dict("sys.modules", git=m):
@@ -1459,3 +1471,79 @@ def test_launch_no_url_job_or_docker_image(
         )
     except wandb.errors.LaunchError as e:
         assert "Must specify a uri, job or docker image" in str(e)
+
+
+@pytest.fixture
+def mocked_fetchable_git_repo_main():
+    """Gross fixture for explicit branch name -- TODO: fix using parameterization (?)"""
+    m = mock.Mock()
+
+    def populate_dst_dir(dst_dir):
+        repo = mock.Mock()
+        reference = mock.Mock()
+        reference.name = "main"
+        repo.references = [reference]
+
+        def create_remote(o, r):
+            origin = mock.Mock()
+            origin.refs = {"main": mock.Mock()}
+            return origin
+
+        repo.create_remote = create_remote
+        repo.heads = {"main": mock.Mock()}
+
+        with open(os.path.join(dst_dir, "train.py"), "w") as f:
+            f.write(fixture_open("train.py").read())
+        with open(os.path.join(dst_dir, "requirements.txt"), "w") as f:
+            f.write(fixture_open("requirements.txt").read())
+        with open(os.path.join(dst_dir, "patch.txt"), "w") as f:
+            f.write("test")
+        return repo
+
+    m.Repo.init = mock.Mock(side_effect=populate_dst_dir)
+    with mock.patch.dict("sys.modules", git=m):
+        yield m
+
+
+def test_launch_git_version_branch_set(
+    live_mock_server, test_settings, mocked_fetchable_git_repo, mock_load_backend
+):
+    api = wandb.sdk.internal.internal_api.Api(
+        default_settings=test_settings, load_settings=False
+    )
+    mock_with_run_info = launch.run(
+        api=api, uri="https://foo:bar@github.com/FooTest/Foo.git", version="foobar"
+    )
+
+    assert "foobar" in str(mock_with_run_info.args[0].git_version)
+
+
+def test_launch_git_version_default_master(
+    live_mock_server, test_settings, mocked_fetchable_git_repo, mock_load_backend
+):
+    api = wandb.sdk.internal.internal_api.Api(
+        default_settings=test_settings, load_settings=False
+    )
+    mock_with_run_info = launch.run(
+        api=api,
+        uri="https://foo:bar@github.com/FooTest/Foo.git",
+    )
+
+    assert "master" in str(mock_with_run_info.args[0].git_version)
+
+
+def test_launch_git_version_default_main(
+    live_mock_server,
+    test_settings,
+    mocked_fetchable_git_repo_main,
+    mock_load_backend,
+):
+    api = wandb.sdk.internal.internal_api.Api(
+        default_settings=test_settings, load_settings=False
+    )
+    mock_with_run_info = launch.run(
+        api=api,
+        uri="https://foo:bar@github.com/FooTest/Foo.git",
+    )
+
+    assert "main" in str(mock_with_run_info.args[0].git_version)
diff --git a/wandb/sdk/launch/_project_spec.py b/wandb/sdk/launch/_project_spec.py
index 7af9d03decf..0a17967d25d 100644
--- a/wandb/sdk/launch/_project_spec.py
+++ b/wandb/sdk/launch/_project_spec.py
@@ -295,11 +295,13 @@ def _fetch_project_local(self, internal_api: Api) -> None:
                     raise LaunchError(
                         "Reproducing a run requires either an associated git repo or a code artifact logged with `run.log_code()`"
                     )
-                utils._fetch_git_repo(
+                branch_name = utils._fetch_git_repo(
                     self.project_dir,
                     run_info["git"]["remote"],
                     run_info["git"]["commit"],
                 )
+                if self.git_version is None:
+                    self.git_version = branch_name
                 patch = utils.fetch_project_diff(
                     source_entity, source_project, source_run_name, internal_api
                 )
@@ -365,7 +367,11 @@ def _fetch_project_local(self, internal_api: Api) -> None:
                     f"{LOG_PREFIX}Entry point for repo not specified, defaulting to python main.py"
                 )
                 self.add_entry_point(["python", "main.py"])
-            utils._fetch_git_repo(self.project_dir, self.uri, self.git_version)
+            branch_name = utils._fetch_git_repo(
+                self.project_dir, self.uri, self.git_version
+            )
+            if self.git_version is None:
+                self.git_version = branch_name
 
 
 class EntryPoint:
diff --git a/wandb/sdk/launch/utils.py b/wandb/sdk/launch/utils.py
index d698cab32ae..e7521934893 100644
--- a/wandb/sdk/launch/utils.py
+++ b/wandb/sdk/launch/utils.py
@@ -11,7 +11,7 @@
 import wandb
 from wandb import util
 from wandb.apis.internal import Api
-from wandb.errors import CommError, ExecutionError, LaunchError
+from wandb.errors import CommError, LaunchError
 
 if TYPE_CHECKING:  # pragma: no cover
     from wandb.apis.public import Artifact as PublicArtifact
@@ -413,7 +413,7 @@ def apply_patch(patch_string: str, dst_dir: str) -> None:
         raise wandb.Error("Failed to apply diff.patch associated with run.")
 
 
-def _fetch_git_repo(dst_dir: str, uri: str, version: Optional[str]) -> None:
+def _fetch_git_repo(dst_dir: str, uri: str, version: Optional[str]) -> str:
     """Clones the git repo at ``uri`` into ``dst_dir``.
 
     checks out commit ``version`` (or defaults to the head commit of the repository's
@@ -428,19 +428,40 @@ def _fetch_git_repo(dst_dir: str, uri: str, version: Optional[str]) -> None:
     repo = git.Repo.init(dst_dir)
     origin = repo.create_remote("origin", uri)
     origin.fetch()
+
     if version is not None:
         try:
             repo.git.checkout(version)
         except git.exc.GitCommandError as e:
-            raise ExecutionError(
+            raise LaunchError(
                 "Unable to checkout version '%s' of git repo %s"
                 "- please ensure that the version exists in the repo. "
                 "Error: %s" % (version, uri, e)
             )
     else:
-        repo.create_head("master", origin.refs.master)
-        repo.heads.master.checkout()
+        if repo.getattr("references", None) is not None:
+            branches = [ref.name for ref in repo.references]
+        else:
+            branches = []
+        # Check if main is in origin, else set branch to master
+        if "main" in branches or "origin/main" in branches:
+            version = "main"
+        else:
+            version = "master"
+
+        try:
+            repo.create_head(version, origin.refs[version])
+            repo.heads[version].checkout()
+            wandb.termlog(f"No git branch passed. Defaulted to branch: {version}")
+        except (AttributeError, IndexError) as e:
+            raise LaunchError(
+                "Unable to checkout default version '%s' of git repo %s "
+                "- to specify a git version use: --git-version \n"
+                "Error: %s" % (version, uri, e)
+            )
+
     repo.submodule_update(init=True, recursive=True)
+    return version
 
 
 def merge_parameters(