---
layout: releasenotes
title: Mono 4.0.1 Release Notes
version: 4.0.1
releasedate: '2015-05-14'
---

4.0.1 is the first maintenance release of the 4.0 series

Improvements
------------

* [1727](https://github.com/mono/mono/pull/1727): Fixed DateTime parsing of Xml strings.
* Fixed intrinsic signature checks to take into account the 'this' parameter
* Redesigned profiler buffer flushing and method reporting to provide correctly ordered events to consumers.
* Use the same dwarf<->hw register mapping on x86 for both LLVM and jitted code, the one used by LLVM is the official version.
* Fix decimal comparison by using signed char comparison of signs; Fix size of jmp instruction sequence
* Correctly disable seq points in wrappers on android.
* Improve Visual Basic build support
* Fix the initialization of the pid array in ves_icall_System_Diagnostics_Process_GetProcesses_internal ().
* Avoid calling task_for_pid on osx 10.5+ and ios.
* Improve error checking when setting up class vtable.

Bug Fixes
---------

* [26998](https://bugzilla.xamarin.com/show_bug.cgi?id=26998): Allow abstract base classes in lists
* [28209](https://bugzilla.xamarin.com/show_bug.cgi?id=28209): Fix freeing invalid memory in CreateProcess () if the executable was not found.
* [28557](https://bugzilla.xamarin.com/show_bug.cgi?id=28557): Transition from step over to step into when control leaves managed code.
* [28847](https://bugzilla.xamarin.com/show_bug.cgi?id=28847): Disable deadce in the liveness2 pass as well when compiling for sdb.
* [28918](https://bugzilla.xamarin.com/show_bug.cgi?id=28918): Mark SecurityDeclarations
* [29039](https://bugzilla.xamarin.com/show_bug.cgi?id=29039): First specific culture returned by enumerator was not fully initialized.
* [29177](https://bugzilla.xamarin.com/show_bug.cgi?id=29177): Check SP on thread suspend correctly.
* [29667](https://bugzilla.xamarin.com/show_bug.cgi?id=29667): Remove inappropropriate use of Marshal.SizeOf.

Contributors
------------

Marcos Henrich, Marek Safar, Alexis Christoforides, Alex Rønne Petersen,
Rolf Bjarne Kvinge, Ludovic Henry, João Matos, Sebastien Pouliot,
Mark Probst, jaredpar.