KaTeX parse error - Lost Data. Joplin won't work

Operating system

Windows

Joplin version

3.0.15

Desktop version info

Joplin 3.0.15 (prod, win32)

Client ID: e101ad4ddab4458aac6904f219439aa9
Sync Version: 3
Profile Version: 47
Keychain Supported: Yes

Revision: 598677b

Backup: 1.4.1

What issue do you have?

I lost important data with a "KaTeX parse error" that I didn't hear about until now. If this can't be fixed, I will be forced to stop using Joplin and will have to find a different program. But I don't want to do that as I really like Joplin. But I need to recover this data. I want to be able to trust Joplin.

Here's one of the failed text lines: KaTeX parse error: Expected 'EOF', got '#' at position 40: …) CONFIRMATION #̲:
It was regarding a dollar amount with text included, and a confirmation number.

I searched this error, and one contributor had me try putting some of the text in a code block but that did nothing. I'm not a developer, so perhaps I was supposed to do more. I also tried "tick marks" which is what another topic said to do. That didn't work either. Another topic said to disable "Tools -> Options -> Markdown -> enable math expressions". It didn't work so I rebooted Joplin, but it still failed.

I want to continue to use Joplin - can anyone help? Thank you!

KaTeX is the library Joplin uses to render math expressions. Does disabling them help? (Settings > Markdown > Uncheck "Enable math expressions").

1 Like

Thank you kindly, my friend, but I had already tried disabling "Enable math expressions". I rebooted Joplin after disabling it to see if that would help, but it didn't.
Again, thank you for your kindness, personalizedrefriger!

Does anyone have an answer to this issue? Certainly, I'm not the only one. I want to be able to continue to trust and use Joplin.

How did you "reboot" Joplin? Most Windows users put Joplin into the background and think the closed it.
So what exactly did you do?

Additionally, can you please elaborate how you lost data because of a rendering error? This makes no sense at all.

1 Like

I appreciate you taking the time to answer me! I closed Joplin from the window then the system tray. Nothing was fixed. So I rebooted the whole computer, and it didn't fix anything.
personalizedrefriger (above) was the person who mentioned "render", and I guess I wasn't sure what he meant either, but I tried his solution, and it didn't help.

These below are lines that got corrupted. I had Joplin open and looked at that data and saw it was corrupted. I can't imagine what caused it. They are some financial notes I need to get back. With my steps above, they still didn't reappear. Additionally, I want to be able to trust Joplin that this won't happen ever again. Here are the lines. What do you think?

KaTeX parse error: Expected 'EOF', got '#' at position 40: …) CONFIRMATION #̲:

KaTeX parse error: Expected 'EOF', got '#' at position 40: …) CONFIRMATION #̲:

KaTeX parse error: Expected 'EOF', got '#' at position 40: …) CONFIRMATION #̲:

KaTeX parse error: Expected 'EOF', got '#' at position 40: …) CONFIRMATION #̲:<span style="c…

katex parse error: Expected 'EOF', got '#' at position 40: …) CONFIRMATION #̲:<span style=;" color:="" 25323d="">

Thank you for your help!

Joplin displays "renders" markdown (which is text) into HTML. The question is whether you are using the WYSIWYG editor (richtext) or the markdown editor, which usually shows the markdown on the left and the rendered HTML on the right side - basically a split view.

Unfortunately I can't help with the former, since I have never used it and even removed the button to switch to that editor from my Joplin UI.

What my confusion is based on is the following. Check my example of KaTeX in one of my notes:

(There is one bug where the headings are incorrectly numbered, but that's a different story.)

But now, you can see the KaTeX formula on the top left. If I now change the formula to include a wrong keyword, the formula is not rendered:

But as you can see my note is still there. No data is lost.

2 Likes

Your knowledge of the underbelly of Joplin is simply amazing! I'm sure if you ran into my problem, you would be able to fix it quickly.
I'm different. I came to Joplin from Evernote. I used Evernote to keep my notes and just used the program for my needs and that is all. I had no desire or time to learn all the fancy extra things you could do with Evernote, as I didn't need them.
It's the same when I came to Joplin. I just use Joplin to keep my notes which keeps me organized to do the other things that I need to do in my life. I just use the easy WYSIWYG editor. I've never used the markdown editor. While interesting, I don't have the time to get the incredible knowledge you have for Joplin. I just want to use it. Another problem with using markdown is my lack of knowledge of this programming - I've looked at the 2 lines (starting with "$\sigma =") and can't see any difference in the 2 lines. UPDATE: In looking at the KaTeX error you made and it saying the problem is position 16, I finally saw you added an extra "c" in the "\sqrt" area. Is that how you generated the error?
I'm still going to study what you wrote in this reply to see if there's something I can do to fix what I have now, and if I will be able to trust Joplin again. I'd love to get my data back. If I'm going to be able to use Joplin and trust it, it looks like I need to learn how to use markdown. Perhaps there are some articles or videos regarding my issue (and perhaps how to use markdown), but I haven't found any good ones yet. But I have hope. I really like Joplin and the community and want to stay here.
Again, thank you for your generous assistance!

Yep, I just appended a c to the katex keyword \frac to generate this error.

Many people do. Personally I dislike WYSIWYG editors, but I'm sure there are people on this forum who use the same editor as you and also use KaTeX. They might be able to help with your katex problem.

Sometimes it takes a while yo get an answer. People might not visit the forum every single day and haven't seen your post yet.

I hope that someone with experience with the WYSIWYG editor can help solve your issue.

1 Like

Thank you, Tessus, I appreciate your efforts! I will keep coming back here to see if someone has a solution.

Well, it doesn't look like there is a solution for this. Sadly, I can't trust Joplin. Does anyone know of a reliable alternative? Thank you.