The rule: the library reports the data it was given with OneModelException; everything else is the .NET exception that fits.
| What happened | What is thrown |
|---|---|
| A model file, stream or checkpoint is corrupt, unsupported or inconsistent; a model uses an operator that is missing; inputs do not fit the model; a module cannot be traced | a type derived from OneModelException: OnnxImportException, ModelFormatException, SessionException, CheckpointException (in the training package), TraceException. Each has a Kind enum for the cause. |
| A file is missing, a directory does not exist, access is denied, the disk is full, a stream fails | the BCL's own FileNotFoundException, DirectoryNotFoundException, UnauthorizedAccessException, IOException, never wrapped, from every method that opens a file or reads a stream |
| An argument is wrong (a negative dimension, a null path, a shape that does not fill the values, an option out of range) | ArgumentException and its subclasses (TensorShapeException is one) with the parameter name |
A session, model or traced model is used after Dispose; a tensor's data is read after its storage was released | ObjectDisposedException (StaleTensorException for tensors) |
An operation does not apply to the object's state (an empty tensor's Item, the gradient of an integer tensor) | InvalidOperationException |
Cancellation through a CancellationToken | OperationCanceledException |
So loading a model needs at most:
try { using var model = Model.Load(badModelPath); } catch (FileNotFoundException) { // A file the operating system cannot open is the BCL's own exception, never wrapped. } catch (OneModelException e) { // Everything the library rejects about the data it was given: a corrupt model, an unsupported operator, // a wrong input shape. e.Category says which part; the specific Kind is on the derived type. report = $"{e.Category}: {e.Message}"; }
OneModelException carries Category (which part of the library), and, where the fault is in a file, InputName, Offset (a byte offset, or -1) and FieldPath (for example ModelProto.graph.node[3].attribute[1].t); the message contains them too, with a very long path shortened. SessionException.Operators lists every unsupported operator at once.
Hostile input is survived: truncated or overlong data, bad lengths, absurd shapes, excessive nesting, external-data paths that leave the model's directory, and endless streams all end in one of the types above, never in IndexOutOfRangeException, NullReferenceException, OverflowException or OutOfMemoryException. Set tighter limits with ModelLoadOptions (getting-started.md). The method and the fuzz targets are in the repository's fuzz folder.