Blender Crashes while moving Sliders
Closed, ResolvedPublic

Description

System Information
Windows 10 Pro 64bit
Intel Core i7-2600K CPU
16GB RAM
Geforce GTX980

Blender Version
Broken: 2.78c Date: 2017-02-24 14:33
Engine: Cycles
Worked: (optional)

A Crash ocures when a Slider is moved

Step1: Create a mesh with a texture
Step2: Add a Convertor - Colorramp to the colorinput of the Defuse Shader
Step3: Add a mapping node to the input of the colorramp
Step4: Add a Texturecoordinate node to the input of the mapping node
Step5: I added a second colorramp between the first colorramp and the Defuse shader because this seams to increases the chance that the error appears. But it's not necessary.
Step6: Change displaymode of 3D View to Material so that the Colors are visible. I'm not sure if that is necessary. It had also once crashed when the mode where set to rendered. I didn't tried it in solidmode.
Step7: Adding some colorpoints to the colorramp and moving them around. Then I closed the nodeeditor and swaped to the properties area on the right where the sliders also are under the materialsettings
After a minute of moving sliders around the crash appeared. Sometimes it crashes just after one second of moving a slider. Once it crashed just after I connected the colorramp to an other node.
This is a Screenshot of the VisualBasic Debugger


Sometimes it is possible to click on Continue and Blender works further like nothing happened.
Otherwise the Error repeats endlessly.
This is my Testfile:

It's only a new File with a rectangular mesh and a texture.

I tried different things to get around this error.
I tried different rendersettings.
I lowered the polrate of my mouse from 1000 to 250.
I tried different graphics drivers.
My first Blender version was 2.68 I think. And I'm not sure when the error first appeared. But I'm sure that it also happened in the last Version witch would have been 2.77
I use Blender also on an other machine. On a minimac with bootcamp and windows 10. The Error never occured there.

I really hope this will be fixed!

Thank you!

Vuk Gardašević (lijenstina) triaged this task as Confirmed priority.May 4 2017, 11:11 PM

I can confirm this bug with the provided blend. Moving the color sliders around moderately fast will eventually crash Blender.

ERROR: Python context internal state bug. this should not happen!
ERROR: Python context internal state bug. this should not happen!
ERROR: Python context internal state bug. this should not happen!
Error: EXCEPTION_ACCESS_VIOLATION

I have a similar issue with Blender Color wheel on Win 7 64 bit , R7 360 build f1ada2e

Default cube > switch to Cycles > Add a material > In the Material tab of Properties editor find the Surface > Color and click on it. The Color widget will show up. . The combination of moving the mouse moderately fast in the color wheel while holding the left button with the occasional release, and then resuming holding it down will lead to the crash - that can on my machine be replicated reliably. Sometimes helps going out the widget border so the position gets clamped from time to time.

At times, it crashes really fast, sometimes after several tries of 10 seconds. Scaling the UI helps with not loosing the mouse focus

I can't get the exact sequence of the crash sometimes a few fast clicks can trigger the bug, in other cases circular movements in a relatively small area of the wheel - but it is probably related on how the update is handled memory wise.

ED_undo_push: Color
ED_undo_push: Color
ED_undo_push: Input value used for unconnected socket
ED_undo_push: Color
Memoryblock free: pointer not in memlist
Error: EXCEPTION_ACCESS_VIOLATION

ED_undo_push: Color
ED_undo_push: Color
ED_undo_push: Color
ED_undo_push: Color
ED_undo_push: Color
ED_undo_push: Color
ED_undo_push: Color
ED_undo_push: Color
Memoryblock ButsTextureUser: double free

ED_undo_push: Color
Memoryblock mesh: Additional error in header
Memoryblock Additional error in header: error in header

This bug show that is not only related to the Color /Wheel Picker Widget but also to the slider of the color ramp.

I will add to this, the fact that Blender can crash while preview rendering on any rapid change in any value (it doesn't matter if it's on the color ramp node or not).

This has also been an issue with the Cycles' rendered view for years. I thought about reporting it before, but the bug was hard to pin down until I found this entry.