diff --git a/packages/functions/src/callable.test.ts b/packages/functions/src/callable.test.ts
index 0de1334b655..eda81d53bdf 100644
--- a/packages/functions/src/callable.test.ts
+++ b/packages/functions/src/callable.test.ts
@@ -35,6 +35,7 @@ import {
 import { makeFakeApp, createTestService } from '../test/utils';
 import { httpsCallable } from './service';
 import { FUNCTIONS_TYPE } from './constants';
+import { FunctionsError } from './error';
 
 // eslint-disable-next-line @typescript-eslint/no-require-imports
 export const TEST_PROJECT = require('../../../config/project.json');
@@ -52,9 +53,10 @@ async function expectError(
     await promise;
   } catch (e) {
     failed = true;
-    expect(e.code).to.equal(`${FUNCTIONS_TYPE}/${code}`);
-    expect(e.message).to.equal(message);
-    expect(e.details).to.deep.equal(details);
+    const error = e as FunctionsError;
+    expect(error.code).to.equal(`${FUNCTIONS_TYPE}/${code}`);
+    expect(error.message).to.equal(message);
+    expect(error.details).to.deep.equal(details);
   }
   if (!failed) {
     expect(false, 'Promise should have failed.').to.be.true;
diff --git a/packages/remote-config/src/api.ts b/packages/remote-config/src/api.ts
index 3bedf579548..aeae67d450e 100644
--- a/packages/remote-config/src/api.ts
+++ b/packages/remote-config/src/api.ts
@@ -123,7 +123,7 @@ export async function fetchConfig(remoteConfig: RemoteConfig): Promise<void> {
 
     await rc._storageCache.setLastFetchStatus('success');
   } catch (e) {
-    const lastFetchStatus = hasErrorCode(e, ErrorCode.FETCH_THROTTLE)
+    const lastFetchStatus = hasErrorCode(e as Error, ErrorCode.FETCH_THROTTLE)
       ? 'throttle'
       : 'failure';
     await rc._storageCache.setLastFetchStatus(lastFetchStatus);
diff --git a/packages/storage/src/platform/node/connection.ts b/packages/storage/src/platform/node/connection.ts
index a656a9f6f84..5a80e90e280 100644
--- a/packages/storage/src/platform/node/connection.ts
+++ b/packages/storage/src/platform/node/connection.ts
@@ -69,7 +69,7 @@ abstract class FetchConnection<T extends ConnectionType>
       this.errorCode_ = ErrorCode.NO_ERROR;
       this.body_ = await response.arrayBuffer();
     } catch (e) {
-      this.errorText_ = e.message;
+      this.errorText_ = (e as Error)?.message;
       // emulate XHR which sets status to 0 when encountering a network error
       this.statusCode_ = 0;
       this.errorCode_ = ErrorCode.NETWORK_ERROR;
@@ -171,7 +171,7 @@ export class FetchStreamConnection extends FetchConnection<NodeJS.ReadableStream
       this.errorCode_ = ErrorCode.NO_ERROR;
       this.stream_ = response.body;
     } catch (e) {
-      this.errorText_ = e.message;
+      this.errorText_ = (e as Error)?.message;
       // emulate XHR which sets status to 0 when encountering a network error
       this.statusCode_ = 0;
       this.errorCode_ = ErrorCode.NETWORK_ERROR;
diff --git a/packages/storage/src/task.ts b/packages/storage/src/task.ts
index 62689856153..e35ee579b40 100644
--- a/packages/storage/src/task.ts
+++ b/packages/storage/src/task.ts
@@ -275,7 +275,7 @@ export class UploadTask {
           this._makeProgressCallback()
         );
       } catch (e) {
-        this._error = e;
+        this._error = e as StorageError;
         this._transition(InternalTaskState.ERROR);
         return;
       }
diff --git a/packages/storage/test/browser/blob.test.ts b/packages/storage/test/browser/blob.test.ts
index b6c56eafa66..1662d452e7f 100644
--- a/packages/storage/test/browser/blob.test.ts
+++ b/packages/storage/test/browser/blob.test.ts
@@ -114,7 +114,7 @@ describe('Firebase Storage > Blob', () => {
       await getBlob(reference);
       expect.fail();
     } catch (e) {
-      expect(e.message).to.satisfy((v: string) =>
+      expect((e as Error)?.message).to.satisfy((v: string) =>
         v.match(/Object 'public\/exp-bytes-missing' does not exist/)
       );
     }
diff --git a/packages/storage/test/integration/integration.test.ts b/packages/storage/test/integration/integration.test.ts
index 80082470dac..27d285b2709 100644
--- a/packages/storage/test/integration/integration.test.ts
+++ b/packages/storage/test/integration/integration.test.ts
@@ -103,7 +103,7 @@ describe('FirebaseStorage Exp', () => {
       await getBytes(reference);
       expect.fail();
     } catch (e) {
-      expect(e.message).to.satisfy((v: string) =>
+      expect((e as Error)?.message).to.satisfy((v: string) =>
         v.match(/Object 'public\/exp-bytes-missing' does not exist/)
       );
     }
@@ -130,7 +130,7 @@ describe('FirebaseStorage Exp', () => {
       await uploadString(reference, 'foo');
       expect.fail();
     } catch (e) {
-      expect(e.message).to.satisfy((v: string) =>
+      expect((e as Error)?.message).to.satisfy((v: string) =>
         v.match(
           /The operation 'uploadString' cannot be performed on a root reference/
         )
diff --git a/packages/storage/test/node/stream.test.ts b/packages/storage/test/node/stream.test.ts
index bbde160692a..65b2fee1498 100644
--- a/packages/storage/test/node/stream.test.ts
+++ b/packages/storage/test/node/stream.test.ts
@@ -68,7 +68,7 @@ describe('Firebase Storage > getStream', () => {
       await readData(stream);
       expect.fail();
     } catch (e) {
-      expect(e.message).to.satisfy((v: string) =>
+      expect((e as Error)?.message).to.satisfy((v: string) =>
         v.match(/Object 'public\/exp-bytes-missing' does not exist/)
       );
     }
diff --git a/packages/storage/test/unit/testshared.ts b/packages/storage/test/unit/testshared.ts
index 1ff22a03b5b..1aa6a53e32a 100644
--- a/packages/storage/test/unit/testshared.ts
+++ b/packages/storage/test/unit/testshared.ts
@@ -156,7 +156,7 @@ export function assertThrows(f: () => void, code: string): StorageError {
     try {
       f();
     } catch (e) {
-      captured = e;
+      captured = e as StorageError;
       throw e;
     }
   }).to.throw();