On Windows 10, I upgraded RC from 2.17.1 to 2.17.7 by manually downloading and launching the installer. After that I was missing pl_PL spellchecking option, so I downloaded some dictionaries from the Internet and tried to install them. Immediately I got an error about RC not being able to install the dictionary files.

After messing around, digging here and there and trying launching as an Administrator (nothing helped) I noticed somewhere, that RC should load dictionaries from C:\Users\USERNAME\AppData\Roaming\Rocket.Chat\dictionaries, but I didn't have that directory. I created it and only after this I was able to install the dictionaries from dic/aif files.
Custom Spell checking dictionaries won't install until the dictionaries folder is created manually.
The dictionaries folder should be created already after installation or should be automatically created when loading dictionaries.
Yes, I described it in https://github.com/RocketChat/Rocket.Chat.Electron/issues/1497#issuecomment-586094019 and https://github.com/RocketChat/Rocket.Chat.Electron/issues/1520#issuecomment-586111288
By default dictionaries folder in path c:\Users\UserName\AppData\Roaming\Rocket.Chat\dictionaries do not exist, and it is can be a bug.
Hi !
Same here, but I'm on macOS Catalina 10.15.3 with Rocket.Chat 2.17.9
Where should I put the dictionaries files on macOS ?
Is it in ~/Library/Containers/chat.rocket/Data/Library/Application Support/Rocket.Chat/ ?
But there is no "dictionaries" folder.
Thanks
I am/was still facing this problem of the missing folder dictionaries with Client version 1.17.11 on Windows 10.
Maybe this error prevented the loading of the Rocket.Chat Client sometimes and only a forced reload (Ctrl+Shift+R) achieved a full loading of the Rocket.Chat UI. It could have been a coincidence, though.
This error was reported in dev tools:
app.js:6156 Error: ENOENT: no such file or directory, scandir 'C:\Users\MyUsername\AppData\Roaming\Rocket.Chat\dictionaries'
getPairsOfDictionaryFiles @ app.js:6156
After creating the missing directory the UI was loading without problems since then. But still: could be an coincidence.
Fixed in 3.0

Most helpful comment
Yes, I described it in https://github.com/RocketChat/Rocket.Chat.Electron/issues/1497#issuecomment-586094019 and https://github.com/RocketChat/Rocket.Chat.Electron/issues/1520#issuecomment-586111288
By default dictionaries folder in path c:\Users\UserName\AppData\Roaming\Rocket.Chat\dictionaries do not exist, and it is can be a bug.