diff --git a/packages/build/src/npm-packages.spec.ts b/packages/build/src/npm-packages.spec.ts
index b41ed44a8..4e33789f6 100644
--- a/packages/build/src/npm-packages.spec.ts
+++ b/packages/build/src/npm-packages.spec.ts
@@ -36,6 +36,17 @@ describe('npm-packages', () => {
       }
       expect.fail('Expected error');
     });
+
+    it('ignores errors when asked to for ENOENT', () => {
+      const result = spawnSync('notaprogram', [], { encoding: 'utf8' }, true);
+      expect(result).to.not.be.undefined;
+    });
+
+    it('ignores errors when asked to for non-zero exit code', () => {
+      const result = spawnSync('bash', ['-c', 'exit 1'], { encoding: 'utf8' }, true);
+      expect(result).to.not.be.undefined;
+      expect(result?.status).to.equal(1);
+    });
   });
 
   describe('bumpNpmPackages', () => {
diff --git a/packages/build/src/npm-packages.ts b/packages/build/src/npm-packages.ts
index a2837a45e..f8746bc98 100644
--- a/packages/build/src/npm-packages.ts
+++ b/packages/build/src/npm-packages.ts
@@ -13,18 +13,30 @@ export interface LernaPackageDescription {
   location: string;
 }
 
-export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding): SpawnSyncReturns<string> {
+export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding): SpawnSyncReturns<string>;
+export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding, ignoreErrors: false): SpawnSyncReturns<string>;
+export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding, ignoreErrors: true): SpawnSyncReturns<string> | undefined;
+export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding, ignoreErrors = false): SpawnSyncReturns<string> | undefined {
   const result = spawn.sync(command, args, options);
   if (result.error) {
     console.error('spawn.sync returned error', result.error);
     console.error(result.stdout);
     console.error(result.stderr);
-    throw new Error(`Failed to spawn ${command}, args: ${args.join(',')}: ${result.error}`);
+
+    if (!ignoreErrors) {
+      throw new Error(`Failed to spawn ${command}, args: ${args.join(',')}: ${result.error}`);
+    } else {
+      console.warn('Ignoring error and continuing...');
+    }
   } else if (result.status !== 0) {
     console.error('spawn.sync exited with non-zero', result.status);
     console.error(result.stdout);
     console.error(result.stderr);
-    throw new Error(`Spawn exited non-zero for ${command}, args: ${args.join(',')}: ${result.status}`);
+    if (!ignoreErrors) {
+      throw new Error(`Spawn exited non-zero for ${command}, args: ${args.join(',')}: ${result.status}`);
+    } else {
+      console.warn('Ignoring error and continuing...');
+    }
   }
   return result;
 }
@@ -138,7 +150,7 @@ export function markBumpedFilesAsAssumeUnchanged(
       stdio: 'inherit',
       cwd: PROJECT_ROOT,
       encoding: 'utf8'
-    });
+    }, true);
     console.info(`File ${f} is now ${assumeUnchanged ? '' : 'NOT '}assumed to be unchanged`);
   });
 }