The viewer tends to crash, mostly after a moment when the app is on the background. It seems related to llvertexbuffer The same is happening on multiple Mac configurations Here is a partial crash log: Thread 0 Crashed:: Dispatch queue: OpenGLMT 0 <translation info unavailable> 0x10c14f978 ??? 1 libsystem_platform.dylib 0x7ff80361beb3 _sigtramp + 51 2 AppleMetalOpenGLRenderer 0x123ec49b3 GLDContextRec::testFence(GLDFenceRec*, int) + 27 3 GLEngine 0x7ffa21b5c76e gleTestSync + 149 4 GLEngine 0x7ffa21acd471 glWaitSync_ListExec + 22 5 GLEngine 0x7ffa21b4e80a gleCmdProcessor + 80 6 libdispatch.dylib 0x7ff80343f7e2 _dispatch_client_callout + 8 7 libdispatch.dylib 0x7ff80344c8f2 _dispatch_lane_barrier_sync_invoke_and_complete + 60 8 GLEngine 0x7ffa21abd580 glDeleteBuffers_ExecThread + 25 9 Second Life Release 0x103ef5e08 delete_buffers(int, unsigned int*) + 392 10 Second Life Release 0x103efbec6 LLAppleVBOPool::free(unsigned int, unsigned int, unsigned int, unsigned char*) + 54 11 Second Life Release 0x103ef5040 LLVertexBuffer::~LLVertexBuffer() + 176 12 Second Life Release 0x103ef570e LLVertexBuffer::~LLVertexBuffer() + 14 13 Second Life Release 0x1028ba2cf LLPointer<LLVertexBuffer>::unref() + 79 14 Second Life Release 0x103ea8bbd LLFontVertexBuffer::reset() + 77 15 Second Life Release 0x103f2738d LLComboBox::setCurrentByIndex(int) + 221 16 Second Life Release 0x103f266bc LLComboBox::add(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&, EAddPosition, bool) + 236 17 Second Life Release 0x102f68c91 LLFloaterTools::updatePopup(LLCoord<LL_COORD_TYPE_GL>, unsigned int) + 1281 18 Second Life Release 0x103a18673 LLViewerWindow::updateLayout() + 307 19 Second Life Release 0x103a15cac LLViewerWindow::updateUI() + 11532 20 Second Life Release 0x102a1d5a9 LLAppViewer::idle() + 1561 21 Second Life Release 0x102a1b89e LLAppViewer::doFrame() + 1918 22 Second Life Release 0x102a1acc7 LLAppViewer::frame() + 55 23 Second Life Release 0x1029c5fcf -[LLAppDelegate oneFrame] + 15