diff --git a/dawn.json b/dawn.json
index aa26700..1686917 100644
--- a/dawn.json
+++ b/dawn.json
@@ -521,6 +521,11 @@
                 ]
             },
             {
+                "name": "create error buffer",
+                "returns": "buffer",
+                "TODO": "enga@: Make this part of a dawn_wire extension"
+            },
+            {
                 "name": "create buffer mapped",
                 "returns": "create buffer mapped result",
                 "args": [
diff --git a/src/dawn_native/Buffer.cpp b/src/dawn_native/Buffer.cpp
index 4df366a..3c97655 100644
--- a/src/dawn_native/Buffer.cpp
+++ b/src/dawn_native/Buffer.cpp
@@ -210,7 +210,7 @@
     void BufferBase::CallMapReadCallback(uint32_t serial,
                                          WGPUBufferMapAsyncStatus status,
                                          const void* pointer,
-                                         uint32_t dataLength) {
+                                         uint64_t dataLength) {
         ASSERT(!IsError());
         if (mMapReadCallback != nullptr && serial == mMapSerial) {
             ASSERT(mMapWriteCallback == nullptr);
@@ -231,7 +231,7 @@
     void BufferBase::CallMapWriteCallback(uint32_t serial,
                                           WGPUBufferMapAsyncStatus status,
                                           void* pointer,
-                                          uint32_t dataLength) {
+                                          uint64_t dataLength) {
         ASSERT(!IsError());
         if (mMapWriteCallback != nullptr && serial == mMapSerial) {
             ASSERT(mMapReadCallback == nullptr);
diff --git a/src/dawn_native/Buffer.h b/src/dawn_native/Buffer.h
index b05e341..8a1feb7 100644
--- a/src/dawn_native/Buffer.h
+++ b/src/dawn_native/Buffer.h
@@ -71,11 +71,11 @@
         void CallMapReadCallback(uint32_t serial,
                                  WGPUBufferMapAsyncStatus status,
                                  const void* pointer,
-                                 uint32_t dataLength);
+                                 uint64_t dataLength);
         void CallMapWriteCallback(uint32_t serial,
                                   WGPUBufferMapAsyncStatus status,
                                   void* pointer,
-                                  uint32_t dataLength);
+                                  uint64_t dataLength);
 
         void DestroyInternal();
 
diff --git a/src/dawn_native/Device.cpp b/src/dawn_native/Device.cpp
index 697b741..7a0d04e 100644
--- a/src/dawn_native/Device.cpp
+++ b/src/dawn_native/Device.cpp
@@ -731,6 +731,12 @@
         return result;
     }
 
+    // For Dawn Wire
+
+    BufferBase* DeviceBase::CreateErrorBuffer() {
+        return BufferBase::MakeError(this);
+    }
+
     // Other Device API methods
 
     void DeviceBase::Tick() {
diff --git a/src/dawn_native/Device.h b/src/dawn_native/Device.h
index b94f762..94d916f 100644
--- a/src/dawn_native/Device.h
+++ b/src/dawn_native/Device.h
@@ -158,6 +158,9 @@
         TextureViewBase* CreateTextureView(TextureBase* texture,
                                            const TextureViewDescriptor* descriptor);
 
+        // For Dawn Wire
+        BufferBase* CreateErrorBuffer();
+
         QueueBase* GetDefaultQueue();
 
         void InjectError(wgpu::ErrorType type, const char* message);
diff --git a/src/dawn_native/d3d12/ResourceAllocatorManagerD3D12.cpp b/src/dawn_native/d3d12/ResourceAllocatorManagerD3D12.cpp
index 1b01a07..4e48f2e 100644
--- a/src/dawn_native/d3d12/ResourceAllocatorManagerD3D12.cpp
+++ b/src/dawn_native/d3d12/ResourceAllocatorManagerD3D12.cpp
@@ -185,8 +185,12 @@
         ResourceHeapAllocation directAllocation;
         DAWN_TRY_ASSIGN(directAllocation,
                         CreateCommittedResource(heapType, resourceDescriptor, initialUsage));
+        if (directAllocation.GetInfo().mMethod != AllocationMethod::kInvalid) {
+            return std::move(directAllocation);
+        }
 
-        return std::move(directAllocation);
+        // If direct allocation fails, the system is probably out of memory.
+        return DAWN_OUT_OF_MEMORY_ERROR("Allocation failed");
     }
 
     void ResourceAllocatorManager::Tick(Serial completedSerial) {
diff --git a/src/dawn_native/vulkan/BufferVk.cpp b/src/dawn_native/vulkan/BufferVk.cpp
index cd35b4c..0b9385e 100644
--- a/src/dawn_native/vulkan/BufferVk.cpp
+++ b/src/dawn_native/vulkan/BufferVk.cpp
@@ -148,7 +148,7 @@
         createInfo.pQueueFamilyIndices = 0;
 
         Device* device = ToBackend(GetDevice());
-        DAWN_TRY(CheckVkSuccess(
+        DAWN_TRY(CheckVkOOMThenSuccess(
             device->fn.CreateBuffer(device->GetVkDevice(), &createInfo, nullptr, &*mHandle),
             "vkCreateBuffer"));
 
diff --git a/src/dawn_native/vulkan/ResourceMemoryAllocatorVk.cpp b/src/dawn_native/vulkan/ResourceMemoryAllocatorVk.cpp
index cff7434..22523a3 100644
--- a/src/dawn_native/vulkan/ResourceMemoryAllocatorVk.cpp
+++ b/src/dawn_native/vulkan/ResourceMemoryAllocatorVk.cpp
@@ -14,6 +14,7 @@
 
 #include "dawn_native/vulkan/ResourceMemoryAllocatorVk.h"
 
+#include "common/Math.h"
 #include "dawn_native/BuddyMemoryAllocator.h"
 #include "dawn_native/ResourceHeapAllocator.h"
 #include "dawn_native/vulkan/DeviceVk.h"
@@ -28,8 +29,7 @@
         // TODO(cwallez@chromium.org): This is a hardcoded heurstic to choose when to
         // suballocate but it should ideally depend on the size of the memory heaps and other
         // factors.
-        constexpr uint64_t kMaxBuddySystemSize = 32ull * 1024ull * 1024ull * 1024ull;  // 32GB
-        constexpr uint64_t kMaxSizeForSubAllocation = 4ull * 1024ull * 1024ull;        // 4MB
+        constexpr uint64_t kMaxSizeForSubAllocation = 4ull * 1024ull * 1024ull;  // 4MiB
 
         // Have each bucket of the buddy system allocate at least some resource of the maximum
         // size
@@ -42,10 +42,18 @@
 
     class ResourceMemoryAllocator::SingleTypeAllocator : public ResourceHeapAllocator {
       public:
-        SingleTypeAllocator(Device* device, size_t memoryTypeIndex)
+        SingleTypeAllocator(Device* device, size_t memoryTypeIndex, VkDeviceSize memoryHeapSize)
             : mDevice(device),
               mMemoryTypeIndex(memoryTypeIndex),
-              mBuddySystem(kMaxBuddySystemSize, kBuddyHeapsSize, this) {
+              mMemoryHeapSize(memoryHeapSize),
+              mBuddySystem(
+                  // Round down to a power of 2 that's <= mMemoryHeapSize. This will always
+                  // be a multiple of kBuddyHeapsSize because kBuddyHeapsSize is a power of 2.
+                  uint64_t(1) << Log2(mMemoryHeapSize),
+                  // Take the min in the very unlikely case the memory heap is tiny.
+                  std::min(uint64_t(1) << Log2(mMemoryHeapSize), kBuddyHeapsSize),
+                  this) {
+            ASSERT(IsPowerOfTwo(kBuddyHeapsSize));
         }
         ~SingleTypeAllocator() override = default;
 
@@ -62,6 +70,10 @@
 
         ResultOrError<std::unique_ptr<ResourceHeapBase>> AllocateResourceHeap(
             uint64_t size) override {
+            if (size > mMemoryHeapSize) {
+                return DAWN_OUT_OF_MEMORY_ERROR("Allocation size too large");
+            }
+
             VkMemoryAllocateInfo allocateInfo;
             allocateInfo.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
             allocateInfo.pNext = nullptr;
@@ -87,6 +99,7 @@
       private:
         Device* mDevice;
         size_t mMemoryTypeIndex;
+        VkDeviceSize mMemoryHeapSize;
         BuddyMemoryAllocator mBuddySystem;
     };
 
@@ -97,7 +110,8 @@
         mAllocatorsPerType.reserve(info.memoryTypes.size());
 
         for (size_t i = 0; i < info.memoryTypes.size(); i++) {
-            mAllocatorsPerType.emplace_back(std::make_unique<SingleTypeAllocator>(mDevice, i));
+            mAllocatorsPerType.emplace_back(std::make_unique<SingleTypeAllocator>(
+                mDevice, i, info.memoryHeaps[info.memoryTypes[i].heapIndex].size));
         }
     }
 
diff --git a/src/dawn_wire/client/ApiProcs.cpp b/src/dawn_wire/client/ApiProcs.cpp
index 6106901..64f6f56 100644
--- a/src/dawn_wire/client/ApiProcs.cpp
+++ b/src/dawn_wire/client/ApiProcs.cpp
@@ -54,12 +54,25 @@
         uint32_t serial = buffer->requestSerial++;
         ASSERT(buffer->requests.find(serial) == buffer->requests.end());
 
+        if (buffer->size > std::numeric_limits<size_t>::max()) {
+            // On buffer creation, we check that mappable buffers do not exceed this size.
+            // So this buffer must not have mappable usage. Inject a validation error.
+            ClientDeviceInjectError(reinterpret_cast<WGPUDevice>(buffer->device),
+                                    WGPUErrorType_Validation,
+                                    "Buffer needs the correct map usage bit");
+            callback(WGPUBufferMapAsyncStatus_Error, nullptr, 0, userdata);
+            return;
+        }
+
         // Create a ReadHandle for the map request. This is the client's intent to read GPU
         // memory.
         MemoryTransferService::ReadHandle* readHandle =
-            buffer->device->GetClient()->GetMemoryTransferService()->CreateReadHandle(buffer->size);
+            buffer->device->GetClient()->GetMemoryTransferService()->CreateReadHandle(
+                static_cast<size_t>(buffer->size));
         if (readHandle == nullptr) {
-            callback(WGPUBufferMapAsyncStatus_DeviceLost, nullptr, 0, userdata);
+            ClientDeviceInjectError(reinterpret_cast<WGPUDevice>(buffer->device),
+                                    WGPUErrorType_OutOfMemory, "Failed to create buffer mapping");
+            callback(WGPUBufferMapAsyncStatus_Error, nullptr, 0, userdata);
             return;
         }
 
@@ -84,13 +97,25 @@
         uint32_t serial = buffer->requestSerial++;
         ASSERT(buffer->requests.find(serial) == buffer->requests.end());
 
+        if (buffer->size > std::numeric_limits<size_t>::max()) {
+            // On buffer creation, we check that mappable buffers do not exceed this size.
+            // So this buffer must not have mappable usage. Inject a validation error.
+            ClientDeviceInjectError(reinterpret_cast<WGPUDevice>(buffer->device),
+                                    WGPUErrorType_Validation,
+                                    "Buffer needs the correct map usage bit");
+            callback(WGPUBufferMapAsyncStatus_Error, nullptr, 0, userdata);
+            return;
+        }
+
         // Create a WriteHandle for the map request. This is the client's intent to write GPU
         // memory.
         MemoryTransferService::WriteHandle* writeHandle =
             buffer->device->GetClient()->GetMemoryTransferService()->CreateWriteHandle(
-                buffer->size);
+                static_cast<size_t>(buffer->size));
         if (writeHandle == nullptr) {
-            callback(WGPUBufferMapAsyncStatus_DeviceLost, nullptr, 0, userdata);
+            ClientDeviceInjectError(reinterpret_cast<WGPUDevice>(buffer->device),
+                                    WGPUErrorType_OutOfMemory, "Failed to create buffer mapping");
+            callback(WGPUBufferMapAsyncStatus_Error, nullptr, 0, userdata);
             return;
         }
 
@@ -112,6 +137,13 @@
         Device* device = reinterpret_cast<Device*>(cDevice);
         Client* wireClient = device->GetClient();
 
+        if ((descriptor->usage & (WGPUBufferUsage_MapRead | WGPUBufferUsage_MapWrite)) != 0 &&
+            descriptor->size > std::numeric_limits<size_t>::max()) {
+            ClientDeviceInjectError(cDevice, WGPUErrorType_OutOfMemory,
+                                    "Buffer is too large for map usage");
+            return ClientDeviceCreateErrorBuffer(cDevice);
+        }
+
         auto* bufferObjectAndSerial = wireClient->BufferAllocator().New(device);
         Buffer* buffer = bufferObjectAndSerial->object.get();
         // Store the size of the buffer so that mapping operations can allocate a
@@ -136,15 +168,18 @@
         Device* device = reinterpret_cast<Device*>(cDevice);
         Client* wireClient = device->GetClient();
 
-        auto* bufferObjectAndSerial = wireClient->BufferAllocator().New(device);
-        Buffer* buffer = bufferObjectAndSerial->object.get();
-        buffer->size = descriptor->size;
-
         WGPUCreateBufferMappedResult result;
-        result.buffer = reinterpret_cast<WGPUBuffer>(buffer);
         result.data = nullptr;
         result.dataLength = 0;
 
+        // This buffer is too large to be mapped and to make a WriteHandle for.
+        if (descriptor->size > std::numeric_limits<size_t>::max()) {
+            ClientDeviceInjectError(cDevice, WGPUErrorType_OutOfMemory,
+                                    "Buffer is too large for mapping");
+            result.buffer = ClientDeviceCreateErrorBuffer(cDevice);
+            return result;
+        }
+
         // Create a WriteHandle for the map request. This is the client's intent to write GPU
         // memory.
         std::unique_ptr<MemoryTransferService::WriteHandle> writeHandle =
@@ -152,7 +187,9 @@
                 wireClient->GetMemoryTransferService()->CreateWriteHandle(descriptor->size));
 
         if (writeHandle == nullptr) {
-            // TODO(enga): Support context lost generated by the client.
+            ClientDeviceInjectError(cDevice, WGPUErrorType_OutOfMemory,
+                                    "Buffer mapping allocation failed");
+            result.buffer = ClientDeviceCreateErrorBuffer(cDevice);
             return result;
         }
 
@@ -161,15 +198,21 @@
         // Open the WriteHandle. This returns a pointer and size of mapped memory.
         // |result.data| may be null on error.
         std::tie(result.data, result.dataLength) = writeHandle->Open();
-
         if (result.data == nullptr) {
-            // TODO(enga): Support context lost generated by the client.
+            ClientDeviceInjectError(cDevice, WGPUErrorType_OutOfMemory,
+                                    "Buffer mapping allocation failed");
+            result.buffer = ClientDeviceCreateErrorBuffer(cDevice);
             return result;
         }
 
+        auto* bufferObjectAndSerial = wireClient->BufferAllocator().New(device);
+        Buffer* buffer = bufferObjectAndSerial->object.get();
+        buffer->size = descriptor->size;
         // Successfully created staging memory. The buffer now owns the WriteHandle.
         buffer->writeHandle = std::move(writeHandle);
 
+        result.buffer = reinterpret_cast<WGPUBuffer>(buffer);
+
         // Get the serialization size of the WriteHandle.
         size_t handleCreateInfoLength = buffer->writeHandle->SerializeCreateSize();
 
diff --git a/src/dawn_wire/client/ClientInlineMemoryTransferService.cpp b/src/dawn_wire/client/ClientInlineMemoryTransferService.cpp
index bfd6634..e773710 100644
--- a/src/dawn_wire/client/ClientInlineMemoryTransferService.cpp
+++ b/src/dawn_wire/client/ClientInlineMemoryTransferService.cpp
@@ -43,7 +43,10 @@
                     return false;
                 }
 
-                mStagingData = std::unique_ptr<uint8_t[]>(new uint8_t[mSize]);
+                mStagingData = std::unique_ptr<uint8_t[]>(new (std::nothrow) uint8_t[mSize]);
+                if (!mStagingData) {
+                    return false;
+                }
                 memcpy(mStagingData.get(), deserializePointer, mSize);
 
                 ASSERT(data != nullptr);
@@ -74,7 +77,10 @@
             }
 
             std::pair<void*, size_t> Open() override {
-                mStagingData = std::unique_ptr<uint8_t[]>(new uint8_t[mSize]);
+                mStagingData = std::unique_ptr<uint8_t[]>(new (std::nothrow) uint8_t[mSize]);
+                if (!mStagingData) {
+                    return std::make_pair(nullptr, 0);
+                }
                 memset(mStagingData.get(), 0, mSize);
                 return std::make_pair(mStagingData.get(), mSize);
             }
diff --git a/src/tests/end2end/BufferTests.cpp b/src/tests/end2end/BufferTests.cpp
index ceaf27c..e854c44 100644
--- a/src/tests/end2end/BufferTests.cpp
+++ b/src/tests/end2end/BufferTests.cpp
@@ -463,17 +463,6 @@
     EXPECT_BUFFER_U32_EQ(myData, result.buffer, 0);
 }
 
-// Test that creating a very large buffers fails gracefully.
-TEST_P(CreateBufferMappedTests, LargeBufferFails) {
-    // TODO(http://crbug.com/dawn/27): Missing support.
-    DAWN_SKIP_TEST_IF(IsOpenGL());
-
-    wgpu::BufferDescriptor descriptor;
-    descriptor.size = std::numeric_limits<uint64_t>::max();
-    descriptor.usage = wgpu::BufferUsage::MapRead | wgpu::BufferUsage::CopyDst;
-    ASSERT_DEVICE_ERROR(device.CreateBuffer(&descriptor));
-}
-
 // Test that creating a zero-sized buffer mapped is allowed.
 TEST_P(CreateBufferMappedTests, ZeroSized) {
     wgpu::BufferDescriptor descriptor;
@@ -534,14 +523,148 @@
 }
 
 // Test that creating a very large buffers fails gracefully.
-TEST_P(BufferTests, LargeBufferFails) {
+TEST_P(BufferTests, CreateBufferOOM) {
     // TODO(http://crbug.com/dawn/27): Missing support.
     DAWN_SKIP_TEST_IF(IsOpenGL());
 
     wgpu::BufferDescriptor descriptor;
+    descriptor.usage = wgpu::BufferUsage::CopyDst;
+
     descriptor.size = std::numeric_limits<uint64_t>::max();
-    descriptor.usage = wgpu::BufferUsage::MapRead | wgpu::BufferUsage::CopyDst;
     ASSERT_DEVICE_ERROR(device.CreateBuffer(&descriptor));
+
+    // UINT64_MAX may be special cased. Test a smaller, but really large buffer also fails
+    // This hangs on the Metal AMD driver
+    if (!(IsMetal() && IsAMD())) {
+        descriptor.size = 1ull << 50;
+        ASSERT_DEVICE_ERROR(device.CreateBuffer(&descriptor));
+    }
+}
+
+// Test that a very large CreateBufferMapped fails gracefully.
+TEST_P(BufferTests, CreateBufferMappedOOM) {
+    // TODO(http://crbug.com/dawn/27): Missing support.
+    DAWN_SKIP_TEST_IF(IsOpenGL());
+
+    // Test non-mappable buffer
+    {
+        wgpu::BufferDescriptor descriptor;
+        descriptor.size = 4;
+        descriptor.usage = wgpu::BufferUsage::CopyDst;
+
+        // Control: test a small buffer works.
+        device.CreateBufferMapped(&descriptor);
+
+        // Test an enormous buffer fails
+        descriptor.size = std::numeric_limits<uint64_t>::max();
+        ASSERT_DEVICE_ERROR(device.CreateBufferMapped(&descriptor));
+
+        // UINT64_MAX may be special cased. Test a smaller, but really large buffer also fails
+        // This hangs on the Metal AMD driver
+        if (!(IsMetal() && IsAMD())) {
+            descriptor.size = 1ull << 50;
+            ASSERT_DEVICE_ERROR(device.CreateBufferMapped(&descriptor));
+        }
+    }
+
+    // Test mappable buffer
+    {
+        wgpu::BufferDescriptor descriptor;
+        descriptor.size = 4;
+        descriptor.usage = wgpu::BufferUsage::CopySrc | wgpu::BufferUsage::MapWrite;
+
+        // Control: test a small buffer works.
+        device.CreateBufferMapped(&descriptor);
+
+        // Test an enormous buffer fails
+        descriptor.size = std::numeric_limits<uint64_t>::max();
+        ASSERT_DEVICE_ERROR(device.CreateBufferMapped(&descriptor));
+
+        if (!(IsMetal() && IsAMD())) {
+            // UINT64_MAX may be special cased. Test a smaller, but really large buffer also fails
+            descriptor.size = 1ull << 50;
+            ASSERT_DEVICE_ERROR(device.CreateBufferMapped(&descriptor));
+        }
+    }
+}
+
+// Test that mapping an OOM buffer for reading fails gracefully
+TEST_P(BufferTests, CreateBufferOOMMapReadAsync) {
+    // TODO(http://crbug.com/dawn/27): Missing support.
+    DAWN_SKIP_TEST_IF(IsOpenGL());
+
+    auto RunTest = [this](const wgpu::BufferDescriptor& descriptor) {
+        wgpu::Buffer buffer;
+        ASSERT_DEVICE_ERROR(buffer = device.CreateBuffer(&descriptor));
+
+        bool done = false;
+        ASSERT_DEVICE_ERROR(buffer.MapReadAsync(
+            [](WGPUBufferMapAsyncStatus status, const void* ptr, uint64_t dataLength,
+               void* userdata) {
+                EXPECT_EQ(status, WGPUBufferMapAsyncStatus_Error);
+                EXPECT_EQ(ptr, nullptr);
+                EXPECT_EQ(dataLength, 0u);
+                *static_cast<bool*>(userdata) = true;
+            },
+            &done));
+
+        while (!done) {
+            WaitABit();
+        }
+    };
+
+    // Test an enormous buffer
+    wgpu::BufferDescriptor descriptor;
+    descriptor.usage = wgpu::BufferUsage::CopyDst | wgpu::BufferUsage::MapRead;
+
+    descriptor.size = std::numeric_limits<uint64_t>::max();
+    RunTest(descriptor);
+
+    // UINT64_MAX may be special cased. Test a smaller, but really large buffer also fails
+    // This hangs on the Metal AMD driver
+    if (!(IsMetal() && IsAMD())) {
+        descriptor.size = 1ull << 50;
+        RunTest(descriptor);
+    }
+}
+
+// Test that mapping an OOM buffer for reading fails gracefully
+TEST_P(BufferTests, CreateBufferOOMMapWriteAsync) {
+    // TODO(http://crbug.com/dawn/27): Missing support.
+    DAWN_SKIP_TEST_IF(IsOpenGL());
+
+    auto RunTest = [this](const wgpu::BufferDescriptor& descriptor) {
+        wgpu::Buffer buffer;
+        ASSERT_DEVICE_ERROR(buffer = device.CreateBuffer(&descriptor));
+
+        bool done = false;
+        ASSERT_DEVICE_ERROR(buffer.MapWriteAsync(
+            [](WGPUBufferMapAsyncStatus status, void* ptr, uint64_t dataLength, void* userdata) {
+                EXPECT_EQ(status, WGPUBufferMapAsyncStatus_Error);
+                EXPECT_EQ(ptr, nullptr);
+                EXPECT_EQ(dataLength, 0u);
+                *static_cast<bool*>(userdata) = true;
+            },
+            &done));
+
+        while (!done) {
+            WaitABit();
+        }
+    };
+
+    wgpu::BufferDescriptor descriptor;
+    descriptor.usage = wgpu::BufferUsage::CopySrc | wgpu::BufferUsage::MapWrite;
+
+    // Test an enormous buffer
+    descriptor.size = std::numeric_limits<uint64_t>::max();
+    RunTest(descriptor);
+
+    // UINT64_MAX may be special cased. Test a smaller, but really large buffer also fails
+    // This hangs on the Metal AMD driver
+    if (!(IsMetal() && IsAMD())) {
+        descriptor.size = 1ull << 50;
+        RunTest(descriptor);
+    }
 }
 
 DAWN_INSTANTIATE_TEST(BufferTests,
diff --git a/src/tests/unittests/wire/WireMemoryTransferServiceTests.cpp b/src/tests/unittests/wire/WireMemoryTransferServiceTests.cpp
index 1d7d828..bb1efb6 100644
--- a/src/tests/unittests/wire/WireMemoryTransferServiceTests.cpp
+++ b/src/tests/unittests/wire/WireMemoryTransferServiceTests.cpp
@@ -474,10 +474,9 @@
     // Mock a ReadHandle creation failure
     MockReadHandleCreationFailure();
 
-    // Failed creation of a ReadHandle is a fatal failure and the client synchronously receives a
-    // DEVICE_LOST callback.
-    EXPECT_CALL(*mockBufferMapReadCallback,
-                Call(WGPUBufferMapAsyncStatus_DeviceLost, nullptr, 0, _))
+    // Failed creation of a ReadHandle is a mapping failure and the client synchronously receives
+    // an error callback.
+    EXPECT_CALL(*mockBufferMapReadCallback, Call(WGPUBufferMapAsyncStatus_Error, nullptr, 0, _))
         .Times(1);
 
     wgpuBufferMapReadAsync(buffer, ToMockBufferMapReadCallback, nullptr);
@@ -716,10 +715,9 @@
     // Mock a WriteHandle creation failure
     MockWriteHandleCreationFailure();
 
-    // Failed creation of a WriteHandle is a fatal failure and the client synchronously receives a
-    // DEVICE_LOST callback.
-    EXPECT_CALL(*mockBufferMapWriteCallback,
-                Call(WGPUBufferMapAsyncStatus_DeviceLost, nullptr, 0, _))
+    // Failed creation of a WriteHandle is a mapping failure and the client synchronously receives
+    // an error callback.
+    EXPECT_CALL(*mockBufferMapWriteCallback, Call(WGPUBufferMapAsyncStatus_Error, nullptr, 0, _))
         .Times(1);
 
     wgpuBufferMapWriteAsync(buffer, ToMockBufferMapWriteCallback, nullptr);