[Solved] Failed to start language server in RC8

[wezz19]

I downloaded and ran the RC8 zip for windows and noticed that:
-Missing splashscreen
-Missing colors in the editor
-The language server doesn't start

Tried the following:
-Using both Uno and Nano boards
-Deleted all old arduino folders to get a clean installation
-Enabled language server logging
Using this guide:
https://forum.arduino.cc/t/cpu-utilization-very-high/941187/13?u=wezz19

But none of this seemed to fix it.
I get this in the log every time I open the IDE:

2022-06-28 11:53:12 root INFO [d044d6a1-4348-4d71-813b-f0efe4e7ed33] Start of 0 plugins: 203.1 ms [Finished 3.714 s after frontend start]
2022-06-28 11:53:12 root INFO Starting language server: arduino:avr:uno
2022-06-28 11:53:12 root INFO Failed to start language server for arduino:avr:uno
2022-06-28 11:53:12 root INFO Starting language server: arduino:avr:uno
2022-06-28 11:53:12 root INFO Failed to start language server for arduino:avr:uno
2022-06-28 11:53:12 root INFO Starting language server: arduino:avr:uno
2022-06-28 11:53:12 root INFO Failed to start language server for arduino:avr:uno
2022-06-28 11:53:12 root INFO Starting language server: arduino:avr:uno
2022-06-28 11:53:12 root INFO Failed to start language server for arduino:avr:uno
2022-06-28 11:53:12 root INFO Starting language server: arduino:avr:uno
2022-06-28 11:53:12 root INFO Failed to start language server for arduino:avr:uno
2022-06-28 11:53:12 root INFO Starting language server: arduino:avr:uno
2022-06-28 11:53:12 root INFO Failed to start language server for arduino:avr:uno
2022-06-28 11:53:13 root INFO Frontend application start: 2637.1 ms [Finished 6.808 s after backend start]

I'm about to try a clean installation using the exe also...
EDIT: How strange! Now the missing splashscreen is back and colors in the editor and the language server seems to be running.

Wonder if this was all due to the folder which I started the zip IDE from earlier. Need to investigate

EDIT2: Found the problem. If you run the IDE from a folder containing a '#' in the name, the language server fails to start. Compiling, uploading, serial monitor and everything works though.

[ptillisch]

@wezz19 has now submitted a formal report of this issue to the Arduino IDE developers:

Failed to start language server

Excellent work on identifying the cause of the problem. Thanks for taking the time to share your findings and for reporting the bug to the developers!

[wezz19]

No problem. Glad I can help with something at least.
Probably not that common to use '#' in folder names, so maybe not really a big issue, but I find it useful to group more important folders first, in a clean looking way.

There are also more symbols which are supported in windows for folder names ( ) [ ]. But they cause some problems with EXCEL files, so I guess not even Microsoft have really tested them out.

Let's see if the devs thinks it's worth fixing.

EDIT: ( ) [ ] doesn't seem to cause any problems so I'll stick to using one of them instead