I got this error:"java.lang.NumberFormatException: null". How can I solve?

[Dongkyu Hwangbo]

Hi forks. I just got an unexpected error and I've no idea about the solution so post this thread. please help.

I have different laptop with same environment.(Win10/chrome) BTW, One of my laptop cannot open any AppInventor project like below.

Palette is invisible, and I cannot build *.apk with empty-new project.

This page is 'report bug' when I click pop-up message.

What's the problem? How can I solve?

[Evan Patton]

Hi Dongkyu,

We are aware that some people are having this problem with Windows 10 and Chrome, so thank you for providing this information. If you could provide the following information it may help us address the bug:

1. Do you see the dialog box to report an error only when switching to the Blocks editor, or does it also appear when loading a project into the designer view?

2. You mention that you cannot build after creating an empty project. Does the NumberFormatException error also happen in the blank project?

3. If you have Mozilla Firefox installed, do you also experience this error in Firefox, or does it only occur in Chrome?

Thanks,

Evan

[Dongkyu Hwangbo]

Hi Evan. 

Thanks for your reply. Here is the answer of your question.

1. Just appear when loading a project into the designer view with two or three same error dialog. When I switch to the Blocks editor, no error dialog but Palette section is just invisible.

2. Yes, absolutely.

3. I tried in Chrome, Firefox, Edge (all the latest version) and I can see same error.

Thanks,

Dongkyu

[Evan Patton]

Thank you for the update Dongkyu.

We are actively working on this and will follow up once we have a solution or any further questions.

Evan

[Dongkyu Hwangbo]

Hi Evan. 

Any update is in there?

Dongkyu

[Evan Patton]

Hi Dongkyu,

Unfortunately, we have not been able to replicate this bug at MIT. We are collecting additional information. Would you please follow the steps I've posted here and get back to me?

Thanks,

Evan

[Evan Patton]

Hi Dongkyu,

It appears this issue is due to conflicting version of App Inventor code loading from cache. A few teachers we have worked with have experienced that clearing Chrome's browser cache resolves this problem. Please follow these instructions from Google and let us know if that fixes the issue.

Thanks,

Evan