diff --git a/cli/instance/instance.go b/cli/instance/instance.go
index 37c0d355323..319f21d52be 100644
--- a/cli/instance/instance.go
+++ b/cli/instance/instance.go
@@ -80,6 +80,40 @@ func getInitResponse() (*rpc.InitResp, error) {
 		resp.PlatformsIndexErrors = rescanResp.PlatformsIndexErrors
 	}
 
+	// Init() succeeded but there were errors loading platform indexes,
+	// let's rescan and try again
+	if resp.GetPlatformsIndexErrors() != nil {
+
+		// log each error
+		for _, err := range resp.GetPlatformsIndexErrors() {
+			logrus.Errorf("Error loading platform index: %v", err)
+		}
+
+		// update platform index
+		_, err := commands.UpdateIndex(context.Background(),
+			&rpc.UpdateIndexReq{Instance: resp.GetInstance()}, output.ProgressBar())
+		if err != nil {
+			return nil, errors.Wrap(err, "updating the core index")
+		}
+
+		// rescan
+		rescanResp, err := commands.Rescan(resp.GetInstance().GetId())
+		if err != nil {
+			return nil, errors.Wrap(err, "during rescan")
+		}
+
+		// errors persist
+		if rescanResp.GetPlatformsIndexErrors() != nil {
+			for _, err := range rescanResp.GetPlatformsIndexErrors() {
+				logrus.Errorf("Still errors after rescan: %v", err)
+			}
+		}
+
+		// succeeded, copy over PlatformsIndexErrors in case errors occurred
+		// during rescan
+		resp.PlatformsIndexErrors = rescanResp.PlatformsIndexErrors
+	}
+
 	return resp, nil
 }
 
diff --git a/test/test_board.py b/test/test_board.py
index f97e42122f0..f1e3365b9db 100644
--- a/test/test_board.py
+++ b/test/test_board.py
@@ -449,5 +449,5 @@ def test_board_details_no_flags(run_command):
     assert result.ok
     result = run_command("board details")
     assert not result.ok
-    assert "Error getting board details: parsing fqbn: invalid fqbn:"
+    assert "Error getting board details: parsing fqbn: invalid fqbn:" in result.stderr
     assert result.stdout == ""
diff --git a/test/test_core.py b/test/test_core.py
index e476df23883..ffc0ac70b30 100644
--- a/test/test_core.py
+++ b/test/test_core.py
@@ -99,6 +99,14 @@ def test_core_updateindex_invalid_url(run_command):
     assert result.failed
 
 
+def test_core_install_without_updateindex(run_command):
+    # Missing "core update-index"
+    # Download samd core pinned to 1.8.6
+    result = run_command("core install arduino:samd@1.8.6")
+    assert result.ok
+    assert "Updating index: package_index.json downloaded" in result.stdout
+
+
 @pytest.mark.skipif(
     platform.system() == "Windows", reason="core fails with fatal error: bits/c++config.h: No such file or directory",
 )