# Create/Update .md files -- Unable to open: Assertion Failed: Argument is ‘undefined’ or ‘null’ **URL:** \ **Category:** Bug Reports\ **Created:** [October 30, 2025, 7:54pm UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018 "2025-10-30T19:54:50Z")\ **Posts on this page:** 17\ **Page:** 2
**Author:** ![dolukhanov](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/dolukhanov/32/88152_2.png) [@dolukhanov](https://forum.cursor.com/u/dolukhanov)\ **Post date:** [November 23, 2025, 10:29pm UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/22 "2025-11-23T22:29:23Z")
A workaround I have found is opening the file in a text editor, adding a blank line, saving and then reopening in the Markdown editor. But it’s cumbersome and should be fixed ---
**Author:** ![hasip](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/hasip/32/72577_2.png) [@hasip](https://forum.cursor.com/u/hasip)\ **Post date:** [November 24, 2025, 5:32pm UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/23 "2025-11-24T17:32:34Z")
When this will be fixed please? Whenever I want to edit a md file I see this. Please fix it. ![Screenshot 2025-11-24 at 18.29.06](https://us1.discourse-cdn.com/cursor1/original/3X/2/6/2611f7bbf61e30f1c0227a799d81a6807954ed60.png) Version: 2.1.26 VSCode Version: 1.105.1 Commit: f628a4761be40b8869ca61a6189cafd14756dff0 Date: 2025-11-24T05:39:06.655Z Electron: 37.7.0 Chromium: 138.0.7204.251 Node.js: 22.20.0 V8: 13.8.258.32-electron.0 OS: Darwin arm64 24.6.0 ---
**Author:** ![Autumn\_Leaves](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@Autumn\_Leaves](https://forum.cursor.com/u/Autumn_Leaves)\ **Post date:** [November 30, 2025, 4:23am UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/24 "2025-11-30T04:23:35Z")
Seeing the same issue for months after paid for the annual premium plan, please show some customer obsession and address it! ---
**Author:** ![suyueLucky](https://avatars.discourse-cdn.com/v4/letter/s/7ab992/32.png) [@suyueLucky](https://forum.cursor.com/u/suyueLucky)\ **Post date:** [November 30, 2025, 10:08am UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/25 "2025-11-30T10:08:16Z")
各位！我的已解决！确实如上面一位网友所说的，罪魁祸首是office overview这个插件闹的，经过我一通折腾，问题得已解决： - 在插件管理区卸载office overview - 强制退出cursor（mac电脑） - 几分钟后打开cursor - 在插件市场重新下载安装office overview - 在cursor左栏任选一个md文件，在中间窗格均能正常显示 - 来吧，恢复正常的网友们，回复一个以资鼓励吧！！！ - 另外，谁能联系office overview的作者推出新版修复这个问题？硬生生困扰了大半年时间！！！！ ---
**Author:** ![Travis\_Polland](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/travis_polland/32/98168_2.png) [@Travis\_Polland](https://forum.cursor.com/u/Travis_Polland)\ **Post date:** [December 16, 2025, 7:07am UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/26 "2025-12-16T07:07:31Z")
I’ve seen this a lot since last week… it doesn’t matter. Any MD file I have, or create new, returns the same error message when trying to render it in the editor. ![CleanShot 2025-12-16 at 18.07.05](https://us1.discourse-cdn.com/cursor1/original/3X/6/5/65037f21e841912fbc3a086e25c2b1fa27952f94.jpeg) Version: 2.2.20 VSCode Version: 1.105.1 Commit: b3573281c4775bfc6bba466bf6563d3d498d1070 Date: 2025-12-12T06:29:26.017Z Electron: 37.7.0 Chromium: 138.0.7204.251 Node.js: 22.20.0 V8: 13.8.258.32-electron.0 OS: Darwin arm64 25.2.0 ---
**Author:** ![andrewh](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/andrewh/32/65515_2.png) [@andrewh](https://forum.cursor.com/u/andrewh)\ **Post date:** [December 17, 2025, 12:19am UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/27 "2025-12-17T00:19:34Z")
Hey all - very sorry about this, taking a look ---
**Author:** ![Dave\_Killeen](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/dave_killeen/32/91512_2.png) [@Dave\_Killeen](https://forum.cursor.com/u/Dave_Killeen)\ **Post date:** [December 17, 2025, 12:04pm UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/28 "2025-12-17T12:04:22Z")
Seems to be only when MD files are created automatically and not when manually created. Workaround for me is to use this plugin that opens the MD and the Preview side by side - [GitHub - yzhang-gh/vscode-markdown: Markdown All in One](https://github.com/yzhang-gh/vscode-markdown) It’s bonkers that this has been going on for so long. Thanks for looking into it @andrewh! ---
**Author:** ![Nikhil\_Tayal](https://avatars.discourse-cdn.com/v4/letter/n/f17d59/32.png) [@Nikhil\_Tayal](https://forum.cursor.com/u/Nikhil_Tayal)\ **Post date:** [December 28, 2025, 1:34pm UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/29 "2025-12-28T13:34:28Z")
Simple workaround - Rename the file name ---
**Author:** ![dolukhanov](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/dolukhanov/32/88152_2.png) [@dolukhanov](https://forum.cursor.com/u/dolukhanov)\ **Post date:** [December 28, 2025, 1:50pm UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/30 "2025-12-28T13:50:19Z")
Or open with text, edit the file and add a space at the end. However, all workarounds. Cursor team - please fix this, it’s been 2 months! ---
**Author:** ![Gunish\_Rai\_Chawla](https://avatars.discourse-cdn.com/v4/letter/g/c89c15/32.png) [@Gunish\_Rai\_Chawla](https://forum.cursor.com/u/Gunish_Rai_Chawla)\ **Post date:** [December 29, 2025, 4:48pm UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/31 "2025-12-29T16:48:22Z")
Very frustrating indeed. Completely disrupts the workflow. There is no reasonable solution. ---
**Author:** ![osbornecox](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/osbornecox/32/92879_2.png) [@osbornecox](https://forum.cursor.com/u/osbornecox)\ **Post date:** [December 30, 2025, 10:25am UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/32 "2025-12-30T10:25:09Z")
same issue here ---
**Author:** ![Greg\_Barnett](https://avatars.discourse-cdn.com/v4/letter/g/5f9b8f/32.png) [@Greg\_Barnett](https://forum.cursor.com/u/Greg_Barnett)\ **Post date:** [January 2, 2026, 5:50pm UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/33 "2026-01-02T17:50:21Z")
Same error for me as well as of Jan 2nd 2026. ---
**Author:** ![user1658](https://avatars.discourse-cdn.com/v4/letter/u/5daacb/32.png) [@user1658](https://forum.cursor.com/u/user1658)\ **Post date:** [January 3, 2026, 6:09am UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/34 "2026-01-03T06:09:48Z")
hello, i rename all my readme.md file to fk\_my\_life.md and it works. thank you. /s ---
**Author:** ![xiao\_bin](https://avatars.discourse-cdn.com/v4/letter/x/d26b3c/32.png) [@xiao\_bin](https://forum.cursor.com/u/xiao_bin)\ **Post date:** [January 9, 2026, 7:44am UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/35 "2026-01-09T07:44:26Z")
我删除了 Office Viewer 插件就好了 ---
**Author:** ![rtabrizi](https://avatars.discourse-cdn.com/v4/letter/r/f14d63/32.png) [@rtabrizi](https://forum.cursor.com/u/rtabrizi)\ **Post date:** [January 14, 2026, 4:55pm UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/36 "2026-01-14T16:55:12Z")
Running into the same issue ---
**Author:** ![Mike\_Clay](https://avatars.discourse-cdn.com/v4/letter/m/ee7513/32.png) [@Mike\_Clay](https://forum.cursor.com/u/Mike_Clay)\ **Post date:** [January 16, 2026, 9:49am UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/37 "2026-01-16T09:49:46Z")
Come on guys. It’s been 3 months now! I’m in the process of recommending tool licensing for my team r/n and this is pushing me to Claude Code as I know this will be a major headache for everyone! ---
**Author:** ![system](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/system/32/99069_2.png) [@system](https://forum.cursor.com/u/system)\ **Post date:** [February 7, 2026, 9:50am UTC](https://forum.cursor.com/t/create-update-md-files-unable-to-open-assertion-failed-argument-is-undefined-or-null/140018/38 "2026-02-07T09:50:34Z")
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