{"record":{"id":"ff3be7851d3d5bb0","repo":"gfx-rs/wgpu","slug":"mismatched-pop-error-scope-call-no-error-scope-fo-ff3be7","errorCode":null,"errorMessage":"Mismatched pop_error_scope call: no error scope for this thread. Error scopes are thread-local.","messagePattern":"Mismatched pop_error_scope call: no error scope for this thread\\. Error scopes are thread-local\\.","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"error","filePath":"wgpu/src/backend/webgpu.rs","lineNumber":2780,"sourceCode":"        let index = self.error_scope_count.get();\n        self.error_scope_count.set(\n            index\n                .checked_add(1)\n                .expect(\"Greater than 2^32 nested error scopes\"),\n        );\n        self.inner.push_error_scope(match filter {\n            crate::ErrorFilter::OutOfMemory => webgpu_sys::GpuErrorFilter::OutOfMemory,\n            crate::ErrorFilter::Validation => webgpu_sys::GpuErrorFilter::Validation,\n            crate::ErrorFilter::Internal => webgpu_sys::GpuErrorFilter::Internal,\n        });\n        index\n    }\n\n    fn pop_error_scope(&self, index: u32) -> Pin<Box<dyn dispatch::PopErrorScopeFuture>> {\n        let current_scope_count = self.error_scope_count.get();\n        let is_panicking = crate::util::is_panicking();\n        if current_scope_count == 0 && !is_panicking {\n            panic!(\"Mismatched pop_error_scope call: no error scope for this thread. Error scopes are thread-local.\");\n        }\n        if index + 1 != current_scope_count && !is_panicking {\n            panic!(\n                \"Mismatched pop_error_scope call: error scopes must be popped in reverse order.\"\n            );\n        }\n        // Decrement the error scope count. We've asserted that the current\n        // size is `index + 1` above.\n        self.error_scope_count.set(index);\n\n        let error_promise = self.inner.pop_error_scope();\n        Box::pin(MakeSendFuture::new(\n            wasm_bindgen_futures::JsFuture::from(error_promise),\n            future_pop_error_scope,\n        ))\n    }\n\n    unsafe fn start_graphics_debugger_capture(&self) {","sourceCodeStart":2762,"sourceCodeEnd":2798,"githubUrl":"https://github.com/gfx-rs/wgpu/blob/3e11ff59bf3f9795d285ecc045014089640d7248/wgpu/src/backend/webgpu.rs#L2762-L2798","documentation":"pop_error_scope panics when the thread-local error scope count is 0 (no matching push) or when scopes are popped out of order. Error scopes in the web backend are tracked per thread, so popping from a different thread than the push, or an extra/mismatched pop, is a programming error rather than a GPU error.","triggerScenarios":"Calling device.pop_error_scope without a preceding push_error_scope on the same thread; pushing on the main thread and popping inside an async callback/worker or wasm task that runs on another thread context; popping two scopes in the wrong order.","commonSituations":"Awaiting pop_error_scope across an async runtime boundary (spawned task) instead of the pushing thread; forgetting a push after early-return code paths; over-popping in nested scope helpers.","solutions":["Ensure every pop_error_scope is called on the same thread as its matching push_error_scope; in async code, await the returned future rather than hopping threads.","Balance push/pop pairs in RAII-style helpers or guaranteed control flow so counts never go negative or out of order.","Pop scopes in reverse order (LIFO) when nesting error scopes."],"exampleFix":"// before\nlet handle = device.push_error_scope(wgpu::ErrorFilter::Validation);\nspawn(async move { let err = handle.pop().await; }); // different thread: panics\n// after\nlet handle = device.push_error_scope(wgpu::ErrorFilter::Validation);\nlet err = handle.pop().await; // same thread, awaited in order","handlingStrategy":"try-catch","validationCode":"// before popping, ensure the current scope exists (app-level counter mirrored from push calls)\nassert!(active_error_scopes.get() > 0, \"no error scope to pop on this thread\");","typeGuard":null,"tryCatchPattern":"// wgpu's pop_error_scope returns a future resolving to Result, but this panic is synchronous;\n// prevent it structurally with an RAII guard:\nstruct ErrorScope<'a> { device: &'a wgpu::Device }\nimpl<'a> ErrorScope<'a> {\n    async fn pop(self) -> Option<wgpu::Error> { self.device.pop_error_scope().await }\n}\nimpl Drop for ErrorScope<'_> { /* ensure balanced push/pop per thread */ }","preventionTips":["Always push and pop error scopes on the same thread; never move the pop future across threads/tasks.","Use an RAII guard or explicit counter so pushes and pops stay balanced and LIFO.","Avoid early returns between push and pop that unbalance the scope stack."],"tags":["webgpu","wasm","error-scope","threading"],"backgroundTag":"mismatched-error-scope-pop","analyzedSha":"3e11ff59bf3f9795d285ecc045014089640d7248","analyzedAt":"2026-09-03T01:43:21.459Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-10T07:17:11.731Z"}