diff --git a/third_party/angle/src/libANGLE/renderer/metal/mtl_state_cache.mm b/third_party/angle/src/libANGLE/renderer/metal/mtl_state_cache.mm
--- a/third_party/angle/src/libANGLE/renderer/metal/mtl_state_cache.mm
+++ b/third_party/angle/src/libANGLE/renderer/metal/mtl_state_cache.mm
@@ -867,12 +867,21 @@ void RenderPassDesc::convertToMetalDesc(MTLRenderPassDescriptor *objCDesc,
     ToObjC(depthAttachment, objCDesc.depthAttachment);
     ToObjC(stencilAttachment, objCDesc.stencilAttachment);

+    // objCDesc is the long-lived mCachedRenderPassDescObjC owned by the
+    // RenderCommandEncoder (allocated once in its constructor, reused for the
+    // lifetime of the ContextMtl). These properties must be reset on every
+    // call, otherwise a value latched by a previous no-attachment render pass
+    // persists into a later pass that has a small attachment, violating the
+    // Metal requirement that renderTargetWidth <= smallest attachment width.
     if ((defaultWidth | defaultHeight) != 0)
     {
         objCDesc.renderTargetWidth        = defaultWidth;
         objCDesc.renderTargetHeight       = defaultHeight;
         objCDesc.defaultRasterSampleCount = 1;
     }
+    else
+    {
+        objCDesc.renderTargetWidth        = 0;
+        objCDesc.renderTargetHeight       = 0;
+        objCDesc.defaultRasterSampleCount = 0;
+    }
 }

diff --git a/third_party/angle/src/libANGLE/renderer/metal/FrameBufferMtl.mm b/third_party/angle/src/libANGLE/renderer/metal/FrameBufferMtl.mm
--- a/third_party/angle/src/libANGLE/renderer/metal/FrameBufferMtl.mm
+++ b/third_party/angle/src/libANGLE/renderer/metal/FrameBufferMtl.mm
@@ -1068,8 +1068,12 @@ angle::Result FramebufferMtl::prepareRenderPass(const gl::Context *context,
     mRenderPassFirstColorAttachmentFormat = nullptr;
     mRenderPassAttachmentsSameColorType   = true;
     uint32_t maxColorAttachments = static_cast<uint32_t>(mState.getColorAttachments().size());
+    // mRenderPassDesc is a persistent member of FramebufferMtl. defaultWidth/
+    // defaultHeight must be reset alongside numColorAttachments and
+    // rasterSampleCount, otherwise a no-attachment pass leaves them set and a
+    // subsequent pass on the same FBO with a small attachment inherits them.
     desc.numColorAttachments     = 0;
     desc.rasterSampleCount       = 1;
+    desc.defaultWidth            = 0;
+    desc.defaultHeight           = 0;
     for (uint32_t colorIndexGL = 0; colorIndexGL < maxColorAttachments; ++colorIndexGL)
     {