On Friday 2022-12-02 on a desktop PC with MS Windows 11 Pro, and runing the Arduino IDE v1.8.19, a sketch
for a M5Stack Core2 would not compile while this sketch built successfully on 2022-04-24.
To investigate the problem, I turned on 'File > Preferences > Show detailed messages during compilation'.
I discovered that the name of the folder of the M5Stack board package contained a '+' character (ASCII decimal value 43, hexadecimal value 2B).
The compiler reported that it could not find (the) file(s). (see below).
As far as I understand it: for the current Microsoft filesystem, NTFS, the '+' character is not a 'reserved character'.
That is probably why there is no error generated when installing the M5Stack board package with the '+' in the name,
however source b above mentions limitations in FAT12, FAT16 and FAT32 file systems. See the text in the most right column,
the text I marked with an orange rectangle. Here the '+' character is listed as 'reserved character'. In other words: one cannot
use the '+' character in file or folder names for these file systems:
Despite a successful install of the M5Stack board package, the compiler was not able to find files because of
the '+' character in the folder name.
Fortunately I was able to install the package with version ID: '2.0.5-1.0'. Next I was able to delete the package with version ID: '2.0.5+1.0'.
After this correction the sketch compiled and built successfully (again)
Here the last part of the build session with the compile error:
The offending folder location and name was:
Today, when using the newest version of the Arduino IDE (version 2.0.3), I was asked to update a boards package from M5Stack.
While the version 2.0.5-1.0 was installed, the Arduino IDE suggested me to install the M5Stack version 2.0.5+1.0. Again the version
with the '+' sign in the version (and sure, the folder name too). With my previous experience I did not install the proposed update. (See the partial screenshot below):
Maybe I address the wrong persons with this post.
Perhaps I should report this problem to the maintainer(s) of the compiler used in the Arduino IDE.
Can I ask the moderators of this M5Stack forum to look into the matter and take corrective measures, if you think that is necessary?