Error writing $$MRU_TOOL_BAR$$.rui.dictionary

I use a lot of scripting with Rhino. I often have multiple instances running scripts at once. Just recently I have a lot of them popping up this error with a modal dialogue upon exiting the instance. This is halting my scripts

Error writing file

Exception: The process cannot access the file because it is being used by another process.

It appears that one of the other opened instances are writing the file at the same time and are locking the file.

This seems to be a newer issue? I heard it was related to the “Last Command Used” toolbar. If I disable that it would probably solve the problem. How do I turn that off?


Hi Curt - that is controlled in Options > Toolbar page > Size and styles.


No, this happens any time two Rhinos are closed in succession - the user isn’t aware of this, but it takes almost 10 seconds for Rhino V6 to write the toolbar file, so if you close a second instance right after the first, you will get that message.

So I tried to hide the “Last Command Used” toolbar using Options > Toolbar page > Size and styles. It did hide it. But didn’t resolve the problem. I’m still getting the error.

This is clearly a sort of concurrency bug that needs fixed. But a workaround would be fine with me.

Is there a way to launch a rhino so that it won’t try to write these files? For scripting I don’t want rhino to save anything, it just performs work and exports some of the resulting geometry to a separate file.