# Jupyterlab: Failed in autocompleting math symbol

**URL:** https://discourse.julialang.org/t/jupyterlab-failed-in-autocompleting-math-symbol/95250
**Category:** Tooling
**Tags:** question
**Created:** [February 27, 2023, 3:02am UTC](https://discourse.julialang.org/t/jupyterlab-failed-in-autocompleting-math-symbol/95250 "2023-02-27T03:02:42Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Strange\_Xue](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@Strange\_Xue](https://discourse.julialang.org/u/Strange_Xue)
#### Post date: [February 27, 2023, 3:02am UTC](https://discourse.julialang.org/t/jupyterlab-failed-in-autocompleting-math-symbol/95250/1 "2023-02-27T03:02:42Z")

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Question 1:  
Look at Gif at below, autocompleting math symbol in jupyterlab is failed.  
 ![example](https://global.discourse-cdn.com/julialang/original/3X/5/f/5ffec9b6fee84343269c599b3f9289c43cc9613c.gif)

Question 2:  
autocompleting math symbol in comments in jupyterlab is failed, the `TAB` can not work.  
 ![example](https://global.discourse-cdn.com/julialang/original/3X/b/3/b34149cbb0ce714eb717c93865893e2872f35f93.gif)

```julia
Julia Version 1.8.5
Commit 17cfb8e65e (2023-01-08 06:45 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: 12 × Intel(R) Core(TM) i5-10400F CPU @ 2.90GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-13.0.1 (ORCJIT, skylake)
  Threads: 12 on 12 virtual cores
Environment:
  JULIA_NUM_THREADS = 12
  JULIA_PKG_SERVER = https://mirrors.ustc.edu.cn/julia

```

```julia
IJulia: v1.24.0

```

```julia
Jupyterlab: 3.6.1
jupyter_server: 2.3.0
browser: vivaldi 5.7.2921.60 (Stable channel) (64-bit) 

```

---

<div class="post-metadata">

### Author: ![cormullion](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/cormullion/32/49131_2.png) [@cormullion](https://discourse.julialang.org/u/cormullion)
#### Post date: [February 28, 2023, 10:46am UTC](https://discourse.julialang.org/t/jupyterlab-failed-in-autocompleting-math-symbol/95250/2 "2023-02-28T10:46:58Z")

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This looks like a bug in JupyterLab. Worth reporting on their github.

If you try to expand a second tab completion for a Unicode point higher than U+1D000 (eg all those maths characters) after some other text in a cell, you see an error with the length of the cell’s text:

```plaintext
KERNEL EXCEPTION
BoundsError: attempt to access 43-codeunit String at index [1:44]

```

that `44` looks like there’s some error processing the entire cell’s text… 🤷

The error doesn’t appear to happen if you’re using IJulia.