diff --git a/dev/conductor/core/lib/src/globals.dart b/dev/conductor/core/lib/src/globals.dart
index 91f76a6a4a..4072c488f1 100644
--- a/dev/conductor/core/lib/src/globals.dart
+++ b/dev/conductor/core/lib/src/globals.dart
@@ -54,7 +54,8 @@ Directory get localFlutterRoot {
   final String checkoutsDirname = fileSystem.path.normalize(
     fileSystem.path.join(
       fileSystem.path.dirname(filePath),
-      '..', // flutter/dev/tools
+      '..', // flutter/dev/conductor/core
+      '..', // flutter/dev/conductor
       '..', // flutter/dev
       '..', // flutter
     ),
diff --git a/dev/conductor/core/lib/src/start.dart b/dev/conductor/core/lib/src/start.dart
index 5a61183494..d48a8c7f92 100644
--- a/dev/conductor/core/lib/src/start.dart
+++ b/dev/conductor/core/lib/src/start.dart
@@ -382,7 +382,8 @@ class StartContext {
     // Get framework version
     final Version lastVersion = Version.fromString(await framework.getFullTag(
         framework.upstreamRemote.name, candidateBranch,
-        exact: false));
+        exact: false,
+    ))..ensureValid(candidateBranch, incrementLetter);
     Version nextVersion;
     if (incrementLetter == 'm') {
       nextVersion = Version.fromCandidateBranch(candidateBranch);
diff --git a/dev/conductor/core/lib/src/version.dart b/dev/conductor/core/lib/src/version.dart
index 20e090ec9e..0389a3f34f 100644
--- a/dev/conductor/core/lib/src/version.dart
+++ b/dev/conductor/core/lib/src/version.dart
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import './globals.dart' show ConductorException;
+import './globals.dart' show releaseCandidateBranchRegex, ConductorException;
 
 /// Possible string formats that `flutter --version` can return.
 enum VersionType {
@@ -251,6 +251,51 @@ class Version {
 
   final VersionType type;
 
+  /// Validate that the parsed version is valid.
+  ///
+  /// Will throw a [ConductorException] if the version is not possible given the
+  /// [candidateBranch] and [incrementLetter].
+  void ensureValid(String candidateBranch, String incrementLetter) {
+    if (!const <String>{'y', 'z', 'm', 'n'}.contains(incrementLetter)) {
+      throw ConductorException('Invalid incrementLetter: $incrementLetter');
+    }
+    final RegExpMatch? branchMatch = releaseCandidateBranchRegex.firstMatch(candidateBranch);
+    if (branchMatch == null) {
+      throw ConductorException(
+        'Candidate branch $candidateBranch does not match the pattern '
+        '${releaseCandidateBranchRegex.pattern}',
+      );
+    }
+
+    // These groups are required in the pattern, so these match groups should
+    // not be null
+    final String branchX = branchMatch.group(1)!;
+    if (x != int.tryParse(branchX)) {
+      throw ConductorException(
+        'Parsed version ${toString()} has a different x value than candidate '
+        'branch $candidateBranch',
+      );
+    }
+    final String branchY = branchMatch.group(2)!;
+    if (y != int.tryParse(branchY)) {
+      throw ConductorException(
+        'Parsed version ${toString()} has a different y value than candidate '
+        'branch $candidateBranch',
+      );
+    }
+
+    // stable type versions don't have an m field set
+    if (type != VersionType.stable && incrementLetter != 'm') {
+      final String branchM = branchMatch.group(3)!;
+      if (m != int.tryParse(branchM)) {
+        throw ConductorException(
+          'Parsed version ${toString()} has a different m value than candidate '
+          'branch $candidateBranch',
+        );
+      }
+    }
+  }
+
   @override
   String toString() {
     switch (type) {
diff --git a/dev/conductor/core/test/start_test.dart b/dev/conductor/core/test/start_test.dart
index a73982567e..3b0ba6906c 100644
--- a/dev/conductor/core/test/start_test.dart
+++ b/dev/conductor/core/test/start_test.dart
@@ -310,7 +310,7 @@ void main() {
       const String revision3 = '123abc';
       const String previousDartRevision = '171876a4e6cf56ee6da1f97d203926bd7afda7ef';
       const String nextDartRevision = 'f6c91128be6b77aef8351e1e3a9d07c85bc2e46e';
-      const String previousVersion = '1.2.0-1.0.pre';
+      const String previousVersion = '1.2.0-3.0.pre';
       const String nextVersion = '1.2.0';
       const String incrementLevel = 'z';
 
diff --git a/dev/conductor/core/test/version_test.dart b/dev/conductor/core/test/version_test.dart
index 3a4c08bd57..7bfa529221 100644
--- a/dev/conductor/core/test/version_test.dart
+++ b/dev/conductor/core/test/version_test.dart
@@ -81,4 +81,77 @@ void main() {
   }, onPlatform: <String, dynamic>{
     'windows': const Skip('Flutter Conductor only supported on macos/linux'),
   });
+
+  group('.ensureValid()', () {
+    test('throws when x does not match', () {
+      const String versionString = '1.2.3-4.5.pre';
+      const String candidateBranch = 'flutter-3.2-candidate.4';
+      final Version version = Version.fromString(versionString);
+      expect(
+        () => version.ensureValid(candidateBranch, 'n'),
+        throwsExceptionWith(
+          'Parsed version $versionString has a different x value than '
+          'candidate branch $candidateBranch',
+        ),
+      );
+    });
+
+    test('throws when y does not match', () {
+      const String versionString = '1.2.3';
+      const String candidateBranch = 'flutter-1.15-candidate.4';
+      final Version version = Version.fromString(versionString);
+      expect(
+        () => version.ensureValid(candidateBranch, 'm'),
+        throwsExceptionWith(
+          'Parsed version $versionString has a different y value than '
+          'candidate branch $candidateBranch',
+        ),
+      );
+    });
+
+    test('throws when m does not match', () {
+      const String versionString = '1.2.3-4.5.pre';
+      const String candidateBranch = 'flutter-1.2-candidate.0';
+      final Version version = Version.fromString(versionString);
+      expect(
+        () => version.ensureValid(candidateBranch, 'n'),
+        throwsExceptionWith(
+          'Parsed version $versionString has a different m value than '
+          'candidate branch $candidateBranch',
+        ),
+      );
+    });
+
+    test('does not validate m if version type is stable', () {
+      const String versionString = '1.2.0';
+      const String candidateBranch = 'flutter-1.2-candidate.98';
+      final Version version = Version.fromString(versionString);
+      expect(
+        () => version.ensureValid(candidateBranch, 'n'),
+        isNot(throwsException),
+      );
+    });
+
+    test('throws on malformed candidate branch', () {
+      const String versionString = '1.2.0';
+      const String candidateBranch = 'stable';
+      final Version version = Version.fromString(versionString);
+      expect(
+        () => version.ensureValid(candidateBranch, 'z'),
+        throwsExceptionWith(
+          'Candidate branch $candidateBranch does not match the pattern',
+        ),
+      );
+    });
+
+    test('does not validate m if incrementLetter is m', () {
+      const String versionString = '1.2.0-0.0.pre';
+      const String candidateBranch = 'flutter-1.2-candidate.42';
+      final Version version = Version.fromString(versionString);
+      expect(
+        () => version.ensureValid(candidateBranch, 'm'),
+        isNot(throwsException),
+      );
+    });
+  });
 }