Common problems

Setup

Failed to connect to BLUX GPU simulation worker. Taichi is probably missing from the Python BLUX picked, or no GPU backend is available. See Cannot connect to the worker.

The Interpreter path shows a red message and is not used. The file must be named like a Python executable (python, pythonw, py or pypy, with an optional version and .exe). BLUX shows which interpreter it uses instead.

Check Solver Environment says Taichi is missing. Install it into the interpreter named under the button: python -m pip install taichi==1.7.4 numpy.

Fracture or demolition fails, or bonds are missing. Impact needs SciPy on both sides. Click Install SciPy in the preferences, and install scipy in the solver Python. See Dependencies.

Liquid surfaces look lumpy or fall back to a simpler mesher. The Production mesher needs pysplashsurf in the solver’s Python. Click Install in the preferences, or see Dependencies.

Running

The first run takes minutes. Taichi compiles the GPU kernels once per solver, then caches them. See Kernel cache and warm-up.

Step, Reset and Bake are greyed out. While the GPU kernels compile in the background, those buttons are unavailable. Hover one to see why. Bake also locks them while a bake is running.

Space does not play the timeline. In the BLUX Physics Graph editor, Space plays or pauses the BLUX simulation instead. In every other editor, Blender’s own keys apply. See Shortcuts and menus.

The simulation looks slow. Atom and Hydro are interactive preview tools: a second of motion costs more than a second of compute. Check the Speed row for the real-time factor. See Time and stability.

A warning appears in red. See Solver warnings.

Templates and graphs

A template erased my graph. Applying a template replaces the current graph and clears the cache. Save a graph preset first. Undo with Ctrl+Z if you have not done anything else.

A node does nothing. The active solver may not read it. A node that the solver ignores shows a warning row. See the compatibility table.

I switched solver and my nodes are unused. Nodes of the other solver stay in the graph but are not read by the new one. Switch back to use them.

Baking and caching

Frames are missing after I change the cache folder. Frames already cached stay in the old folder and are no longer shown. Change the folder before baking.

A Blaze bake from an older version renders too cold. Caches from before a temperature unit change stored temperature in solver units. Re-bake them.

My bake stopped. Use Resume Bake to continue from the last checkpoint. See Bake, upres and checkpoints.

The disk filled up. Lower the Disk Budget in the preferences, or click Clear Cache. At a million particles a frame is about 32 MB. See Cache and budgets.

Rendering

Liquid glass renders black. Raise the Cycles transmission and transparent bounces. See Render settings.

The liquid surface shows an old shape. Changed mesher settings keep showing the previous surface, flagged stale, until you re-mesh. Click Remesh Surface.

Smoke looks soft and noisy. Render volumes at 64 samples or more. The denoiser at low sample counts softens smoke.

I do not see helper objects, wireframes or overlays. They only exist once a graph exists, and they follow the Viewport Overlays toggles. See Viewport display and overlays.

Getting help

Note the exact message and the output of Check Solver Environment. Ask in the BLUX community on Discord, or send a message with the contact form. See Getting help for what to include.