Uploading file give me error.

I use WordPress just a few weeks ago.
Plugin installed and active are : Yoast, Site Kit and Twentig.
WordPress version 5.6.2, Theme Child Twenty Twenty
From the media library, I’m used to upload .xlsb file without problem.
Even last night I’m still able to upload xlsb file.

This morning, when I want to upload another .xlsb file it gave me message :

Unexpected response from the server. The file may have been uploaded successfully. Check in the Media Library or reload the page.

1. Follow the instruction on the message above, still nothing.
2. Refresh then upload again that xlsb file, still the same error.
3. Logout my cPanel, login back, login to WP, upload again, still the same error.
4. Then I upload .gif image file. Succeed.
5. Then I upload .jpg image file. Succeed.
6. Then I upload .txt file, again the same error.
7. Then I upload .png image file. Succeed.
8. Then I upload .xlsx file, again the same error.
9. Then I upload .pdf file. Succeed.
10. Then I upload .xlsm file, again the same error.
11. Then I upload .mid file, the same error.
12. Then I upload again and again and again the xlsb file, the same error.
13. Then suddenly, after trying for the million + 1 times, the xlsb file successfully uploaded.

So I continue my post…
Ooops… I forget to write something in that uploaded xlsb before.
So in my computer I update the xlsb file,
In WP dashboard media library, delete permanently that xlsb file
then upload the updated xlsb file (same name)
then again the same error appear.

So I’m back from number 1 to 12.
Since I never get the number 13, so I write this post :).

What is the cause of that ?
Why it suddenly can “solve” by itself ?
How do I solve that ?

Any kind of help would be greatly appreciated.
Thank you in advanced.

FYI,
I also have tried the upload within the post editor.
the “file” block’s button color looks like in progress (the color fade in fade out), then it show :

The response is not a valid JSON response

.
I go to setting, permalink, then directly just click the button Save Changes a few times. Upload again via post editor, “file” block. The same error and the button color keeps on fading in fading out. But if I upload an image file, it succeed.
I’ve also already tried to clear browser cache, still the same error.

• This topic was modified 3 years, 12 months ago by karmapala.
• This topic was modified 3 years, 12 months ago by karmapala.
• This topic was modified 3 years, 12 months ago by karmapala.
• This topic was modified 3 years, 12 months ago by karmapala.