diff --git a/packages/core/schematics/ng-generate/control-flow-migration/migration.ts b/packages/core/schematics/ng-generate/control-flow-migration/migration.ts
index 31ea72c07f9..4131a8c43ab 100644
--- a/packages/core/schematics/ng-generate/control-flow-migration/migration.ts
+++ b/packages/core/schematics/ng-generate/control-flow-migration/migration.ts
@@ -40,6 +40,7 @@ export function migrateTemplate(
       migrated = formatTemplate(migrated, templateType);
     }
     file.removeCommonModule = canRemoveCommonModule(template);
+    file.canRemoveImports = true;
 
     // when migrating an external template, we have to pass back
     // whether it's safe to remove the CommonModule to the
@@ -48,6 +49,7 @@ export function migrateTemplate(
         analyzedFiles.has(file.sourceFilePath)) {
       const componentFile = analyzedFiles.get(file.sourceFilePath)!;
       componentFile.removeCommonModule = file.removeCommonModule;
+      componentFile.canRemoveImports = file.canRemoveImports;
     }
 
     errors = [
@@ -56,7 +58,7 @@ export function migrateTemplate(
       ...switchResult.errors,
       ...caseResult.errors,
     ];
-  } else {
+  } else if (file.canRemoveImports) {
     migrated = removeImports(template, node, file.removeCommonModule);
   }
 
diff --git a/packages/core/schematics/ng-generate/control-flow-migration/types.ts b/packages/core/schematics/ng-generate/control-flow-migration/types.ts
index 32a27bc15c1..9f74225ca80 100644
--- a/packages/core/schematics/ng-generate/control-flow-migration/types.ts
+++ b/packages/core/schematics/ng-generate/control-flow-migration/types.ts
@@ -240,6 +240,7 @@ export class Template {
 export class AnalyzedFile {
   private ranges: Range[] = [];
   removeCommonModule = false;
+  canRemoveImports = false;
   sourceFilePath: string = '';
 
   /** Returns the ranges in the order in which they should be migrated. */
diff --git a/packages/core/schematics/test/control_flow_migration_spec.ts b/packages/core/schematics/test/control_flow_migration_spec.ts
index fe723573b82..af93b372e1d 100644
--- a/packages/core/schematics/test/control_flow_migration_spec.ts
+++ b/packages/core/schematics/test/control_flow_migration_spec.ts
@@ -4638,6 +4638,55 @@ describe('control flow migration', () => {
       expect(actual).toBe(expected);
     });
 
+    it('should not remove common module imports post migration if errors prevented migrating the external template file',
+       async () => {
+         writeFile('/comp.ts', [
+           `import {Component} from '@angular/core';`,
+           `import {NgIf} from '@angular/common';`,
+           `@Component({`,
+           `  imports: [NgIf],`,
+           `  templateUrl: './comp.html',`,
+           `})`,
+           `class Comp {`,
+           `  toggle = false;`,
+           `}`,
+         ].join('\n'));
+
+         writeFile('/comp.html', [
+           `<div>`,
+           `  <span *ngIf="toggle; else elseTmpl">shrug</span>`,
+           `</div>`,
+           `<ng-template #elseTmpl>else content</ng-template>`,
+           `<ng-template #elseTmpl>different</ng-template>`,
+         ].join('\n'));
+
+         await runMigration();
+         const actualCmp = tree.readContent('/comp.ts');
+         const expectedCmp = [
+           `import {Component} from '@angular/core';`,
+           `import {NgIf} from '@angular/common';`,
+           `@Component({`,
+           `  imports: [NgIf],`,
+           `  templateUrl: './comp.html',`,
+           `})`,
+           `class Comp {`,
+           `  toggle = false;`,
+           `}`,
+         ].join('\n');
+         const actualTemplate = tree.readContent('/comp.html');
+
+         const expectedTemplate = [
+           `<div>`,
+           `  <span *ngIf="toggle; else elseTmpl">shrug</span>`,
+           `</div>`,
+           `<ng-template #elseTmpl>else content</ng-template>`,
+           `<ng-template #elseTmpl>different</ng-template>`,
+         ].join('\n');
+
+         expect(actualCmp).toBe(expectedCmp);
+         expect(actualTemplate).toBe(expectedTemplate);
+       });
+
     it('should not remove common module imports post migration if other items used', async () => {
       writeFile('/comp.ts', [
         `import {CommonModule} from '@angular/common';`,