System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.ArgumentException: dst.Size != src.Size
at Pinta.Core.BinaryPixelOp.Apply (Cairo.ImageSurface dst, Cairo.ImageSurface src) <0x40aca260 + 0x00107> in <filename unknown>:0
at Pinta.Core.Document.GetFlattenedImage () <0x40aca090 + 0x00137> in <filename unknown>:0
at Pinta.Core.GdkPixbufFormat.Export (Pinta.Core.Document document, System.String fileName, Gtk.Window parent) <0x40ac9ff0 + 0x0002b> in <filename unknown>:0
at Pinta.Actions.SaveDocumentImplmentationAction.SaveFile (Pinta.Core.Document document, System.String file, Pinta.Core.FormatDescriptor format, Gtk.Window parent) <0x40ac9980 + 0x0039a> in <filename unknown>:0
at Pinta.Actions.SaveDocumentImplmentationAction.SaveFileAs (Pinta.Core.Document document) <0x40ac6a90 + 0x00a17> in <filename unknown>:0
at Pinta.Actions.SaveDocumentImplmentationAction.Activated (System.Object sender, Pinta.Core.DocumentCancelEventArgs e) <0x40ac6970 + 0x0005b> in <filename unknown>:0
at Pinta.Core.FileActions.RaiseSaveDocument (Pinta.Core.Document document, Boolean saveAs) <0x40ac6830 + 0x0006d> in <filename unknown>:0
at Pinta.Core.Document.Save (Boolean saveAs) <0x40ac67e0 + 0x00033> in <filename unknown>:0
at Pinta.Actions.SaveDocumentAsAction.Activated (System.Object sender, System.EventArgs e) <0x40acdbf0 + 0x00027> in <filename unknown>:0
at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) <0x7f3dcfdab9e0 + 0x000a1> in <filename unknown>:0
--- End of inner exception stack trace ---
at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) <0x7f3dcfdab9e0 + 0x000ef> in <filename unknown>:0
at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) <0x7f3dcfbe3cf0 + 0x0002a> in <filename unknown>:0
at System.Delegate.DynamicInvokeImpl (System.Object[] args) <0x7f3dcfe63f60 + 0x0024c> in <filename unknown>:0
at System.MulticastDelegate.DynamicInvokeImpl (System.Object[] args) <0x7f3dcfe6c040 + 0x00035> in <filename unknown>:0
at System.Delegate.DynamicInvoke (System.Object[] args) <0x7f3dcfe63e80 + 0x00019> in <filename unknown>:0
at GLib.Signal.ClosureInvokedCB (System.Object o, GLib.ClosureInvokedArgs args) <0x409fe6b0 + 0x00153> in <filename unknown>:0
at GLib.SignalClosure.Invoke (GLib.ClosureInvokedArgs args) <0x409fe670 + 0x0002f> in <filename unknown>:0
at GLib.SignalClosure.MarshalCallback (IntPtr raw_closure, IntPtr return_val, UInt32 n_param_vals, IntPtr param_values, IntPtr invocation_hint, IntPtr marshal_data) <0x409fd000 + 0x002bb> in <filename unknown>:0
It would be very helpful if you could provide the image together with information about the modifications you made to it before saving. Saving works for my uses cases here, so you must be hitting some corner case.