"internal error..." Adopting Arduino Board Platform

[jarsudsco]

Sloeber V4.4.3 and an existing ESP8266 based project.

I'd been having a problem as in #1554 where ARDUINO_BOARD_ID was not being populated. Jantje said that was fixed as part of #1625 way back in Aug 2024. I have V4/nightly enabled in "Available Software Sites" - is this enough to get such fixes or do I need to do something else. (I've been getting around this by adding a -DARDUINO_BOARD_ID="ESP8266" to the compile options - it throws up a redefined symbol error for every file it compiles but at least it compiles. I don't know what the valid options are for that setting either.)

Then I started getting the library_index.json download errors as in #1731 followed the advice and made a local copy of the file (does the filename matter? Jantje's example was library_index_local.json) and that seemed to fix things until yesterday when the download failed again. (Do I need to remove the official Arduino URL from the list of third party URL's?)

I downloaded a new copy of library_index.json and replaced the previous file, but now I'm getting another error when trying to add the Adafruit Neopixel library to the project, and have come to a dead stop...

[jarsudsco]

I forgot to include a .log

.log

[jantje]

The error is happening while parsing the library_index.
That is why you do not see the libraries as provided by Arduino.
Looking at the log file I can think of 2 reasons why this problem occurs.
Caused by: java.lang.ClassNotFoundException: org.apache.commons.lang3.ArrayUtils cannot be found by org.apache.commons.commons-compress_1.28.0
1)A setup problem making that org.apache.commons.lang3.ArrayUtils is not available on the system
2)A corrupted/not completely downloaded json file.
As these files get downloaded and processed for each and every build here on github this "should work" and again I see 3 reasons why it doesn't in your case
1)You are not running the sloeber product
2)You have updated Sloeber (removing necessary parts in the process)
3)You are experiencing network problems

Which brings me to

Do I need to remove the official Arduino URL from the list of third party URL's?

Absolutely yes.
I added some notes hoping to clear some confusion.
#1731 (comment)