diff --git a/internal/gitview/gitView.go b/internal/gitview/gitView.go
index ae13f6133..8b682e6e9 100644
--- a/internal/gitview/gitView.go
+++ b/internal/gitview/gitView.go
@@ -1,6 +1,7 @@
 package gitview
 
 import (
+	"errors"
 	"fmt"
 	"net/url"
 	"strings"
@@ -45,6 +46,16 @@ type GitView struct {
 
 const redactedCommitInfoValue = "**REDACTED**"
 
+// TODO: remove this guard once go-git supports sha256 (v6) and the Kosli backend accepts sha256 commits.
+
+// ErrUnsupportedObjectFormat is returned by New for a repository using the sha256 object format.
+var ErrUnsupportedObjectFormat = errors.New("the repository uses the sha256 object format, which the Kosli CLI does not support yet")
+
+func isUnsupportedObjectFormat(err error) bool {
+	return (errors.Is(err, git.ErrUnsupportedExtensionRepositoryFormatVersion) || errors.Is(err, git.ErrUnknownExtension)) &&
+		strings.Contains(err.Error(), "objectformat")
+}
+
 // New opens a git repository from the given path. It detects if the
 // repository is bare or a normal one. If the path doesn't contain a valid
 // repository ErrRepositoryNotExists is returned
@@ -52,6 +63,9 @@ func New(repositoryRoot string) (*GitView, error) {
 	repository, err := git.PlainOpenWithOptions(repositoryRoot, &git.PlainOpenOptions{
 		EnableDotGitCommonDir: true,
 	})
+	if isUnsupportedObjectFormat(err) {
+		return nil, fmt.Errorf("failed to open git repository at %s: %w (%v)", repositoryRoot, ErrUnsupportedObjectFormat, err)
+	}
 	if err != nil {
 		return nil, fmt.Errorf("failed to open git repository at %s: %v", repositoryRoot, err)
 	}
diff --git a/internal/gitview/gitView_test.go b/internal/gitview/gitView_test.go
index 63fc1bbbd..5c465ee3b 100644
--- a/internal/gitview/gitView_test.go
+++ b/internal/gitview/gitView_test.go
@@ -51,6 +51,18 @@ func (suite *GitViewTestSuite) TestNewGitView() {
 
 	_, err = New(filepath.Join(suite.tmpDir, "non-existing"))
 	require.Error(suite.T(), err)
+	require.NotErrorIs(suite.T(), err, ErrUnsupportedObjectFormat)
+}
+
+func (suite *GitViewTestSuite) TestNewGitViewSha256Repo() {
+	dirPath := filepath.Join(suite.tmpDir, "sha256Repo")
+	cmd := exec.Command("git", "init", "--object-format=sha256", dirPath)
+	output, err := cmd.CombinedOutput()
+	require.NoError(suite.T(), err, "git init failed: %s", string(output))
+
+	_, err = New(dirPath)
+	require.ErrorIs(suite.T(), err, ErrUnsupportedObjectFormat)
+	require.Contains(suite.T(), err.Error(), "sha256")
 }
 
 func (suite *GitViewTestSuite) TestNewGitViewFromWorktree() {