{"record":{"id":"4f91bcb8317f5f6d","repo":"tracel-ai/burn","slug":"failed-to-read-tensor-data-as-dtype-err","errorCode":null,"errorMessage":"Failed to read tensor data as {dtype:?}: {err}","messagePattern":"Failed to read tensor data as (.+?): (.+?)","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"error","filePath":"crates/burn-tensor/src/tensor/api/base.rs","lineNumber":2170,"sourceCode":"    }\n\n    /// Copies the tensor data to host memory and converts it to `dtype`.\n    ///\n    /// The conversion is a no-op if the dtype is the same as the current dtype.\n    ///\n    /// See: [`Tensor::try_to_data_dtype`].\n    ///\n    /// # Returns\n    /// A `TensorData` with the requested `dtype`.\n    ///\n    /// # Panics\n    ///\n    /// Panics if synchronous readback isn't supported, tensor execution or storage access fails,\n    /// or the data can't be converted to `dtype`.\n    #[track_caller]\n    pub fn to_data_dtype(&self, dtype: DType) -> TensorData {\n        self.try_to_data_dtype(dtype)\n            .unwrap_or_else(|err| panic!(\"Failed to read tensor data as {dtype:?}: {err}\"))\n    }\n\n    /// Copies the tensor data to host memory and converts it to `dtype`.\n    ///\n    /// By contract, this will yield the same result as\n    /// `tensor.try_to_data()?.try_cast(dtype)`.\n    ///\n    /// The conversion is a no-op if the dtype is the same as the current dtype.\n    ///\n    /// # Errors\n    ///\n    /// Returns an error if tensor execution or storage access fails, or the data can't be\n    /// converted to `dtype`.\n    ///\n    /// # Panics\n    ///\n    /// Panics if the platform doesn't support synchronous readback.\n    pub fn try_to_data_dtype(&self, dtype: DType) -> Result<TensorData, TensorReadError> {","sourceCodeStart":2152,"sourceCodeEnd":2188,"githubUrl":"https://github.com/tracel-ai/burn/blob/d16f7ba2ed0d41408189384044cc886fb4c8f957/crates/burn-tensor/src/tensor/api/base.rs#L2152-L2188","documentation":"Tensor::to_data_dtype(dtype) copies tensor data to the host and converts it to the given DType, panicking with this message if try_to_data_dtype fails. Failure modes are the same as other readbacks (unsupported sync readback, execution/storage error) plus dtype conversion failure. The panic message includes the requested dtype and the underlying error.","triggerScenarios":"Requesting a dtype conversion the backend or Element implementation cannot perform (e.g. converting bool or complex data to an int/float dtype); reading a tensor on a backend lacking synchronous readback; an execution error (failed kernel, OOM) surfacing during the read.","commonSituations":"Downcasting model outputs to f16/bf16 or upcasting int8 quantized tensors to f32 where the cast is unsupported; test harnesses converting tensors to a comparison dtype; GPU pipelines reading intermediates before execution completes.","solutions":["Use try_to_data_dtype(dtype) and handle the Result to avoid the panic","Choose a supported target DType; fall back to manual conversion via to_data() + TensorData::try_cast(dtype)","Confirm the source tensor's dtype supports conversion to the requested one (e.g. numeric-to-numeric)","Verify backend support for sync readback or restructure so the read happens after execution completes"],"exampleFix":"// before\nlet data = tensor.to_data_dtype(DType::F16); // panics if cast/read fails\n// after\nlet data = tensor.try_to_data_dtype(DType::F16)?;","handlingStrategy":"try-catch","validationCode":null,"typeGuard":null,"tryCatchPattern":"match tensor.try_to_data_dtype(dtype) { Ok(d) => ..., Err(e) => ... }","preventionTips":["Prefer try_ variants in production code"],"tags":["tensor","dtype","readback","panic","burn"],"backgroundTag":"tensor-data-readback-failed","analyzedSha":"d16f7ba2ed0d41408189384044cc886fb4c8f957","analyzedAt":"2026-09-05T13:19:14.260Z","contentChangedAt":"2026-09-05T13:19:14.260Z","schemaVersion":2},"datasetVersion":"2026-09-12T17:17:11.597Z"}