# \[Script\] Crashes with selection:deselect() and Undo (Ctrl+Z)
**URL:** https://community.aseprite.org/t/script-crashes-with-selection-deselect-and-undo-ctrl-z/6169
**Category:** Bug Reports
**Created:** [June 17, 2020, 12:22pm UTC](https://community.aseprite.org/t/script-crashes-with-selection-deselect-and-undo-ctrl-z/6169 "2020-06-17T12:22:07Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@msk-k](https://community.aseprite.org/u/msk-k)
#### Post date: [June 17, 2020, 12:22pm UTC](https://community.aseprite.org/t/script-crashes-with-selection-deselect-and-undo-ctrl-z/6169/1 "2020-06-17T12:22:07Z")
## Version Infomation
Aseprite v1.2.20
Surface 6 pro/Windows 10 1903
### Reproduction procedure
1. Execute lua method “app.activeSprite.selection:deselect()” **with nothing selected**.
2. Then Undo (Ctrl+Z) and Aseprite throws an exception and crashes.
(Nothing should have been changed, but Undo will be made.)
### Appendix
[appendix 1.]
The methods that raised the exception as follows.
```auto
aseprite/src/doc/mask.cpp
void Mask::copyFrom(const Mask* sourceMask)
line 120
```
The exception that occurred are as follows.
```auto
Exception has occurred: W32/0xc0000005
Exception thrown: read access violation.
sourceMask was nullptr.
```
I actually debugged it and found that the value of sourceMask was nullptr.
[appendix 2.]
When using the “app.command.DeselectMask()” .
no exceptions are raised under the same conditions.
Because nothing has been changed, I can’t Undo.
=================================
Is this a specification?
If so, you might want to include the following information as a supplementary item in documentation.
“Do not execute app.activeSprite.selection:deselect() with nothing selected.”
---
### Author:  [@dacap](https://community.aseprite.org/u/dacap)
#### Post date: [June 17, 2020, 8:15pm UTC](https://community.aseprite.org/t/script-crashes-with-selection-deselect-and-undo-ctrl-z/6169/2 "2020-06-17T20:15:21Z")
Hi @msk-k, thanks for reporting this bug, there will be fixed in the next release (maybe today).
---
### Author:  [@dacap](https://community.aseprite.org/u/dacap)
#### Post date: [June 17, 2020, 11:32pm UTC](https://community.aseprite.org/t/script-crashes-with-selection-deselect-and-undo-ctrl-z/6169/3 "2020-06-17T23:32:15Z")
Fixed in [Aseprite v1.2.21](https://community.aseprite.org/t/aseprite-v1-2-21/6178)
---
### Author:  [@dacap](https://community.aseprite.org/u/dacap)
#### Post date: [June 17, 2020, 11:32pm UTC](https://community.aseprite.org/t/script-crashes-with-selection-deselect-and-undo-ctrl-z/6169/4 "2020-06-17T23:32:22Z")