I have a simple sketch using an RTC (DS3231) . Compiles and runs fine with IDE 1. Downloaded IDE 2 (beta), rebooted, and A) lots of keywords ( e.g. "serial" and keywords from included libraries) are marked with red underline, B) compiling yields the informative message "Compilation error: Error: 13 INTERNAL: exit status 1". I'll post code if anyone wants, but seems a bit pointless.
This is currently the Arduino IDE 2.x cryptic equivalent of the more intuitive "No such file or directory" error you have probably encountered when using the classic Arduino IDE.
The bug that caused the error message to be so strange has already been fixed, and so this will be a better experience on the next release of Arduino IDE 2.x:
This error almost always means you need to install the library that contains the missing file.
Often the code you're compiling will come with documentation (either a comment or separate document) that tells you where to get the library dependencies.
Note that libraries may have dependencies on other libraries.
In other cases the author of the code will not have been so kind and you'll need to go on a hunt for the missing library.
A good place to start is the Arduino IDE's Library Manager:
Select Sketch > Include Library > Manage Libraries... from the Arduino IDE's menus.
In the "Filter your search..." box, type some keywords you have gleaned from the missing file name.
Scroll through the results for the right library. Click on it.
Click the Install button.
Wait for the installation to finish.
Try compiling your code again.
If you have no luck in Library Manager then load up your favorite search engine and do a search for the missing filename. You will often get multiple results. If you have a lot of results you might add "arduino" as an additional search keyword. I will usually prefer results from github.com since that is where most Arduino libraries are hosted and downloading from there is fast and easy. In some cases there will be multiple libraries that contain the given filename and you'll need to do some evaluation to determine which seems the most appropriate, then try it out.
After downloading the library you found, you'll need to install it. This requires a different process than the Library Manager installation. You will find instructions here:
As for this, it might be that you have a different sketchbook setting in each of the Arduino IDEs. Arduino IDE 2.x has a different preferences storage system than the classic Arduino IDE, so any custom settings you configured in the classic Arduino IDE preferences are not automatically transferred to Arduino IDE 2.x.
Libraries are installed to your sketchbook folder, so if you have a different sketchbook folder then the libraries installed by one IDE will not be available in the other.
You can check the sketchbook folder location by opening File > Preferences from the Arduino IDE menus and then checking the "Sketchbook location" setting.
After a bit of buggering around with pathnames (I hate Win 10! And I didn't ask for OneDrive. Bring back XP!) - it seems to have compiled. I'll come back if there are any more problems.
somewhere along the way you said "yes" to it, as did I
I have learned from hard experience that installing Windows is like walking through a minefield. If you can manage to make it through without accidentally signing up for a Microsoft account and enabling OneDrive and Cortana and Windows Store and Xbox Live and on and on and on, the OS itself really isn't so bad.
That is, after I have spent two full days combing through every setting and registry hack to make it work something like my Window 7 installation, which I had done my best to make work something like my XP installation, which I had done my best to make work like my Windows 95 installation, which I had done my best to make work like my Windows 3.1 installation. So I'm not actually sure what the model is I'm shooting for anymore, but it sure is nothing like the stock installation.