The macOS dictionary app cannot add new build in dictionaries

Go with the solution Marsxue provided. Just delete all the folders under that detection. You will able to install all the dictionaries just like before.

It works! Thank you!

Thanks!

I can finally have my dictionaries back!

@McCoy_Appleseed I can confirm it works for me. thank you so much!

Go with MarsXues answer! Really simple and helpful!

The question is, how can I delete files in the system library?

thank you, whoever you are, you solved my problem

Reinstall the OS didn't work, I have tried it...

Just use the instruction as the main topic said, I already fix it, it's a bug, so reinstall can't fix it

Thank you! I replied before I read the entire thread, lol... I hope Apple will fix this "little" bug soon...

Thank you - this fixed it for me.

My system does not have the file you and others are suggesting, how can I fix that.

Catalina 10.15.4

I have tried every fix in this whole thread and not a single one has worked to fix the Dictionary. I can't believe this is still an issue.

It turns out that all you need to do is delete everything in the following path:

/System/Library/AssetsV2/PreinstalledAssetsV2/InstallWithOs/com_apple_MobileAsset_DictionaryServices_dictionaryOSX

When you reopen the Dictionary app afterwards, all the dictionaries will become selectable, and the app will automatically download the dictionaries selected.