La 1.6.207 è una versione beta col supporto del 328PB. Se non avete quel microcontrollore non serve installarla.L'ultima ufficiale è la 1.6.21.Se via appare la 207 è perché avete aggiunto queste schede --> https://downloads.arduino.cc/packages/package_avr_3.6.0_index.json
ARDUINO 1.8.6 2018.08.23[ide]* Updated arduino-builder to 1.4.0: - parallel build (improve compile speed) - better reuse of already compiled files - Windows: fixed build for sketch stored under OneDrive cloud folders* Added translations for library types. Thanks @ReAlUA* Added scroller in programmers menu.* Added "accelerator" in scrollable menu, press "a" key while scrolling* Keep "Board Manager" menu item always as first in the menu* "Manage Libraries" is now also in the "Tools" menu. Thanks @feikname* Compiler errors now have both column and line* Serial monitor how has "Show Timestamp" option. Thanks @MichalSy* Improved DPI detection for hi-resolution montior on Linux* Added copy/paste contextual menu in Find/Replace text fields* Fixed long IDE startup time when some virtual/not-connected network interfaces are present* Fixed inconsistent line-endings when saving files on Windows* mdns: Make board disappear via TTL instead of reachability. Thanks @kurtgo* Library Manager: display install/remove buttons with mouse on-hover instead of mouse click* Board Manager: fixed some rare case with corrupted index download* Windows: removed some debug output when running the IDE from command line* Support selectable user-defined themes. User's theme are zip files inside the sketchbook "theme" folder* Library Manager: library search now search also for headers (.h) declared by the library in library.properties* Added "--version" to the CLI. Thanks @yohsuke* Fixed Serial Plotter/Monitor permanently disabled if Plotter fails to open* Fixed window title that sometimes is not updated on "Save as...". Thanks @JxJxJxMxNxS* Fixed keybindings for Increase/Decrease font size* Improved accessibility in the Preferences dialog. Thanks @coreyknapp[core]* AVR: Set Optiboot as default bootloader for Nano. This is the bootloader installed on new Arduino Nano boards. If you have a Nano with the old bootloader you must select Tools > Processor > ATmega328P (Old Bootloader) to upload.* AVR core has been moved to its own repository: https://github.com/arduino/ArduinoCore-avr* Updated toolchain to gcc 5.4.0[wifi101-firmware]* SECURITY FIX: Released fix for WPA2 KRACK vulnerability (latest WINC1500 firmware 19.5.2).
Ma sulla tua macchina windows hai provato?