diff --git a/src/actions/bootloader.ts b/src/actions/bootloader.ts
index 206aa134..cfda654e 100644
--- a/src/actions/bootloader.ts
+++ b/src/actions/bootloader.ts
@@ -84,7 +84,7 @@ export interface BootloaderConnectionSendAction
 
 export function send(
     data: ArrayBuffer,
-    withResponse = false,
+    withResponse = true,
 ): BootloaderConnectionSendAction {
     return { type: BootloaderConnectionActionType.Send, data, withResponse };
 }
diff --git a/src/sagas/bootloader.test.ts b/src/sagas/bootloader.test.ts
index e9ee5f01..9bc982f5 100644
--- a/src/sagas/bootloader.test.ts
+++ b/src/sagas/bootloader.test.ts
@@ -146,7 +146,8 @@ describe('message encoder', () => {
         expect(dispatched[0]).toEqual({
             type: BootloaderConnectionActionType.Send,
             data: message,
-            withResponse: false,
+            // Program is write without response, all others are write with response
+            withResponse: request.type !== BootloaderRequestActionType.Program,
         });
     });
 
@@ -185,7 +186,7 @@ describe('message encoder', () => {
             expect(dispatched[i]).toEqual({
                 type: BootloaderConnectionActionType.Send,
                 data: message,
-                withResponse: false,
+                withResponse: true,
             });
         }
 
diff --git a/src/sagas/bootloader.ts b/src/sagas/bootloader.ts
index 3f0a637e..d8b46a6d 100644
--- a/src/sagas/bootloader.ts
+++ b/src/sagas/bootloader.ts
@@ -38,6 +38,7 @@ import {
     checksumResponse,
     connect,
     didRequest,
+    disconnectRequest,
     eraseRequest,
     eraseResponse,
     errorResponse,
@@ -53,6 +54,7 @@ import {
     stateResponse,
 } from '../actions/bootloader';
 import { MpyCompiledAction, compile } from '../actions/mpy';
+import * as notification from '../actions/notification';
 import {
     Command,
     ErrorBytecode,
@@ -92,13 +94,23 @@ function* encodeRequest(): Generator {
     while (true) {
         const action = (yield take(chan)) as BootloaderRequestAction;
 
+        // NB: Commands other than program on city hub will cause BlueZ to
+        // disconnect because they will send a response even if we write without
+        // response, so we always write with response on those commands. The
+        // program command needs to be write without response for performance
+        // reasons (and also the city hub will disconnect if write with response
+        // is used on this command).
+
         switch (action.type) {
             case BootloaderRequestActionType.Erase:
                 yield put(send(createEraseFlashRequest()));
                 break;
             case BootloaderRequestActionType.Program:
                 yield put(
-                    send(createProgramFlashRequest(action.address, action.payload)),
+                    send(
+                        createProgramFlashRequest(action.address, action.payload),
+                        /* withResponse */ false,
+                    ),
                 );
                 break;
             case BootloaderRequestActionType.Reboot:
@@ -294,6 +306,18 @@ function* flashFirmware(action: BootloaderFlashFirmwareAction): Generator {
         );
     }
 
+    // City hub bootloader is buggy. See note in encodeRequest().
+    if (info[0].hubType === HubType.CityHub && !didConnect.canWriteWithoutResponse) {
+        yield put(
+            notification.add(
+                'error',
+                'City Hub is not compatible with this web browser.',
+            ),
+        );
+        yield put(disconnectRequest());
+        return;
+    }
+
     yield put(eraseRequest());
     const erase = (yield wait(
         BootloaderResponseActionType.Erase,
diff --git a/src/services/bootloader.ts b/src/services/bootloader.ts
index 2889a628..c5974369 100644
--- a/src/services/bootloader.ts
+++ b/src/services/bootloader.ts
@@ -86,6 +86,10 @@ async function connect(action: Action, dispatch: Dispatch): Promise<void> {
                 !char.writeValueWithoutResponse &&
                 !/Android/i.test(navigator.userAgent)
             ) {
+                // TODO: this needs to be an error if connected to city hub
+                // however it is not currently possible to get mfg-specific
+                // advertising data, so we don't know what type of hub it is
+                // until after we connect
                 dispatch(
                     notification.add(
                         'warning',