# issue with following height of free surface in VOF simulation, paraview crashes when using plot over time
**URL:** https://discourse.paraview.org/t/issue-with-following-height-of-free-surface-in-vof-simulation-paraview-crashes-when-using-plot-over-time/16003
**Category:** ParaView Support
**Created:** [January 20, 2025, 4:47pm UTC](https://discourse.paraview.org/t/issue-with-following-height-of-free-surface-in-vof-simulation-paraview-crashes-when-using-plot-over-time/16003 "2025-01-20T16:47:31Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@otaolafr](https://discourse.paraview.org/u/otaolafr)
#### Post date: [January 20, 2025, 4:47pm UTC](https://discourse.paraview.org/t/issue-with-following-height-of-free-surface-in-vof-simulation-paraview-crashes-when-using-plot-over-time/16003/1 "2025-01-20T16:47:31Z")
Hello,
I am having issues trying to follow the area of the interface on my VOF simulation.
for this currently I am doing:
1. contour over alpha.air=0.5
2. merge blocks
3. connectivity region neared point at 0,0,0.5
4. integrate values
up to this paraview does not have any errors or issues. but when I apply plot over time filter to integrate values to follow for example the area over time. paraview crashes. and I get this error:
```auto
critical: In unknown, line 0
critical: Cannot open data file " "" "
```
here is the data: [FileSender](https://filesender.renater.fr/?s=download&token=ada273c8-eeab-4d4d-ae96-7592ba9c43b1)
and here is the saved state:
[example.pvsm](https://discourse.paraview.org/uploads/short-url/xdjzaNLv8YSeOP3r3ovXqFVEDfO.pvsm) (692.0 KB)
regards
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [January 20, 2025, 4:59pm UTC](https://discourse.paraview.org/t/issue-with-following-height-of-free-surface-in-vof-simulation-paraview-crashes-when-using-plot-over-time/16003/2 "2025-01-20T16:59:55Z")
I see an issue with ParaView 5.13.1 but the nightly seems to be fixed already:
You can find the nightly here: [https://www.paraview.org/download/?version=nightly](https://www.paraview.org/download/?version=nightly)
---
### Author:  [@otaolafr](https://discourse.paraview.org/u/otaolafr)
#### Post date: [January 20, 2025, 5:06pm UTC](https://discourse.paraview.org/t/issue-with-following-height-of-free-surface-in-vof-simulation-paraview-crashes-when-using-plot-over-time/16003/3 "2025-01-20T17:06:29Z")
Hello mathieu,
I just tested in 5.13.2 and also crashes. I will download the nightly to test.
tested in nightly, can confirm that it nows works.