For some reason, Mathematica has started freezing whenever I try to type anything into it. I can paste text into notebooks, but as soon as I start typing the window will freeze and it will cease to respond.

Why is this, and how can I fix it?

  • $\begingroup$ @MarcoB good catch. Hopefully this one will be a good waymarker to that one. $\endgroup$ Commented Apr 19, 2016 at 10:11

1 Answer 1


I'm not exactly sure why exactly this happens. However, the solution is explained by a Wolfram Community post by Matthias König here, which is buried in a bunch of other things so I thought I would make it easier to find:

The issue is caused by the file that is supposed to make the prediction of your autocomplete better. Go to $UserBaseDirectory/.Mathematica/SystemFiles/FrontEnd/SystemResources /FunctionalFrequency and check the .m-file there. Everytime this happens to me, this file was several hundred MB large. Deleting it solves the problem.

That said, I still have no idea why this became an issue, or how exactly that file (CodeAssistHistory10.3.m) became so bloated.

If you do run into this problem in the future, it's worth pointing out this response by WRI autocompletion engineer Tom Sherlock, indicating that a bug report with the bloated file is probably helpful on the WRI end:

The files in this directory store your autocompletion history to help the system make accurate completions based on your past choices. Several hundred megabytes seems quite excessive. If anyone here encounters this problem again and there is a very large file in this directory, you can help me track down the problem by sending the file into tech support along with a description of the problem (assuming that deleting the file actually does cure the issue). I'll get notified and be better able to fix the issue.

  • 2
    $\begingroup$ Thanks. This just happened to me yesterday and it's always a drag to set up new kernels and all the other preferences when have to delete the whole ./Mathematica directory. This is much better, in case this is the cause as it was in my case. $\endgroup$
    – user21
    Commented Mar 30, 2016 at 22:40

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