diff --git a/profiler-cli/src/daemon.ts b/profiler-cli/src/daemon.ts
index baf0e2b5e0..4a54b6e664 100644
--- a/profiler-cli/src/daemon.ts
+++ b/profiler-cli/src/daemon.ts
@@ -32,6 +32,7 @@ import {
   writeStartupError,
 } from './session';
 import {
+  describeProfileVersionError,
   describeSessionDirFailure,
   describeSocketListenError,
   describeStaleSocketFailure,
@@ -58,12 +59,10 @@ function formatProfileLoadError(error: unknown): string {
     error instanceof ProfileVersionError ||
     (error instanceof Error && error.name === 'ProfileVersionError')
   ) {
-    const versionError = error as ProfileVersionError;
-    return (
-      `This profile is version ${versionError.profileVersion}, but this profiler-cli only ` +
-      `supports up to version ${versionError.supportedVersion} of the ${versionError.formatName} profile format.\n` +
-      `Update to the latest version with:\n` +
-      `  npm install -g ${PACKAGE_NAME}@latest`
+    return describeProfileVersionError(
+      error as ProfileVersionError,
+      PACKAGE_NAME,
+      process.argv[1]
     );
   }
   return error instanceof Error ? error.message : String(error);
diff --git a/profiler-cli/src/diagnostics.ts b/profiler-cli/src/diagnostics.ts
index 1f30b55739..d2dacd3474 100644
--- a/profiler-cli/src/diagnostics.ts
+++ b/profiler-cli/src/diagnostics.ts
@@ -15,6 +15,7 @@
 import * as fs from 'fs';
 import * as os from 'os';
 import * as path from 'path';
+import type { ProfileVersionError } from 'firefox-profiler/profile-logic/errors';
 
 /**
  * Advice shown whenever the failure looks like a sandbox restriction on the
@@ -346,3 +347,58 @@ export function indentBlock(text: string, prefix: string = '  '): string {
     .map((line) => `${prefix}${line}`)
     .join('\n');
 }
+
+/**
+ * Where `./mach` keeps its downloaded tools, including the copies of samply
+ * and profiler-cli that Firefox's bootstrap installs.
+ */
+export function getMozbuildStatePath(): string {
+  return (
+    process.env.MOZBUILD_STATE_PATH || path.join(os.homedir(), '.mozbuild')
+  );
+}
+
+function realpathOrSelf(filePath: string): string {
+  try {
+    return fs.realpathSync(filePath);
+  } catch {
+    return path.resolve(filePath);
+  }
+}
+
+/**
+ * Whether the profiler-cli script at `scriptPath` is the copy that
+ * `./mach bootstrap` installed from Firefox's in-tree toolchain.
+ */
+export function isInstalledByMachBootstrap(scriptPath: string): boolean {
+  const toolDir = realpathOrSelf(
+    path.join(getMozbuildStatePath(), 'profiler-cli')
+  );
+  const relative = path.relative(toolDir, realpathOrSelf(scriptPath));
+  return (
+    relative !== '' && !relative.startsWith('..') && !path.isAbsolute(relative)
+  );
+}
+
+/**
+ * Explain that a profile is too new for this build and how to update it.
+ * The bootstrapped copy can only be updated through "./mach bootstrap".
+ */
+export function describeProfileVersionError(
+  error: ProfileVersionError,
+  packageName: string,
+  scriptPath: string
+): string {
+  const versionLine = `This profile is version ${error.profileVersion}, but this profiler-cli only supports up to version ${error.supportedVersion} of the ${error.formatName} profile format.`;
+  if (isInstalledByMachBootstrap(scriptPath)) {
+    return [
+      versionLine,
+      'This profiler-cli was installed by "./mach bootstrap". Update your Firefox checkout to the latest main branch and run "./mach bootstrap" again.',
+    ].join('\n');
+  }
+  return [
+    versionLine,
+    'Update to the latest version with:',
+    `  npm install -g ${packageName}@latest`,
+  ].join('\n');
+}
diff --git a/profiler-cli/src/samply.ts b/profiler-cli/src/samply.ts
index 8e036713d1..3b619e51f6 100644
--- a/profiler-cli/src/samply.ts
+++ b/profiler-cli/src/samply.ts
@@ -10,8 +10,8 @@
 
 import * as child_process from 'child_process';
 import * as fs from 'fs';
-import * as os from 'os';
 import * as path from 'path';
+import { getMozbuildStatePath } from './diagnostics';
 
 export type SamplyServer = {
   binaryPath: string;
@@ -37,16 +37,6 @@ function isExecutableFile(filePath: string): boolean {
   }
 }
 
-/**
- * Where `./mach` keeps its downloaded tools. Firefox's bootstrap installs
- * samply there, so it is a good fallback when samply is not on PATH.
- */
-function getMozbuildStatePath(): string {
-  return (
-    process.env.MOZBUILD_STATE_PATH || path.join(os.homedir(), '.mozbuild')
-  );
-}
-
 /**
  * Resolve the samply binary: PROFILER_CLI_SAMPLY_PATH if set, then PATH, then
  * the mozbuild state directory. Returns null when none of them has it. An
diff --git a/profiler-cli/src/test/unit/diagnostics.test.ts b/profiler-cli/src/test/unit/diagnostics.test.ts
index 6534c23313..4fc3602dbc 100644
--- a/profiler-cli/src/test/unit/diagnostics.test.ts
+++ b/profiler-cli/src/test/unit/diagnostics.test.ts
@@ -12,6 +12,7 @@ import * as os from 'os';
 import * as path from 'path';
 import {
   assertSocketPathUsable,
+  describeProfileVersionError,
   describeSessionDirFailure,
   describeSocketConnectError,
   describeSocketListenError,
@@ -20,6 +21,8 @@ import {
   getErrnoCode,
   indentBlock,
 } from '../../diagnostics';
+import { ProfileVersionError } from 'firefox-profiler/profile-logic/errors';
+import { snapshotEnv } from '../integration/fake-samply';
 
 function errnoError(code: string, message: string): NodeJS.ErrnoException {
   const error: NodeJS.ErrnoException = new Error(message);
@@ -229,4 +232,51 @@ describe('profiler-cli diagnostics', function () {
       expect(indentBlock('a\nb')).toBe('  a\n  b');
     });
   });
+
+  describe('describeProfileVersionError', function () {
+    const PACKAGE = '@firefox-devtools/profiler-cli';
+    const error = new ProfileVersionError('processed', 78, 77);
+    let restoreEnv: () => void;
+
+    beforeEach(function () {
+      restoreEnv = snapshotEnv(['MOZBUILD_STATE_PATH']);
+      process.env.MOZBUILD_STATE_PATH = path.join(tmpDir, 'mozbuild');
+    });
+
+    afterEach(function () {
+      restoreEnv();
+    });
+
+    it('points npm installs at npm', function () {
+      const message = describeProfileVersionError(
+        error,
+        PACKAGE,
+        path.join(tmpDir, 'npm', 'profiler-cli', 'dist', 'profiler-cli.js')
+      );
+      expect(message).toContain('version 78');
+      expect(message).toContain('up to version 77 of the processed');
+      expect(message).toContain(`npm install -g ${PACKAGE}@latest`);
+      expect(message).not.toContain('mach bootstrap');
+    });
+
+    it('points bootstrapped installs at mach bootstrap', function () {
+      const message = describeProfileVersionError(
+        error,
+        PACKAGE,
+        path.join(tmpDir, 'mozbuild', 'profiler-cli', 'dist', 'profiler-cli.js')
+      );
+      expect(message).toContain('version 78');
+      expect(message).toContain('./mach bootstrap');
+      expect(message).not.toContain('npm install -g');
+    });
+
+    it('does not treat a sibling directory of the bootstrapped copy as bootstrapped', function () {
+      const message = describeProfileVersionError(
+        error,
+        PACKAGE,
+        path.join(tmpDir, 'mozbuild', 'profiler-cli-old', 'profiler-cli.js')
+      );
+      expect(message).not.toContain('mach bootstrap');
+    });
+  });
 });