About a week ago i had the Arduino Wifi Rev2 board connected and running and accepting code. Now i can't see the option listed and i can't program it. I have tried googling and searching for answers, even uninstalling and reinstalling, but i can't get the board option back. Does anyone know what i can do to select the board again? or why it disappeared? Windows still recognizes the Arduino correctly and i still have the port. 
It seems like the Arduino IDE is not able to access the index file via the Internet:
https://downloads.arduino.cc/packages/package_index.json
Even if you had Arduino megaAVR Boards installed already, this can cause the core to no longer be recognized by the Arduino IDE.
Please do this:
- Tools > Board > Boards Manager
- Wait for the download to finish.
- Click the "Close" button.
- Click on the black console window at the bottom of the Arduino IDE window.
- Press "Ctrl + A". This will select all the text in the console window.
- Press "Ctrl + C". This will copy the selected text to the clipboard.
- In a reply here, click the </> button on the forum toolbar. This will insert code tags into the reply field.
- Press "Ctrl + V". This will paste the copied text from the clipboard between the code tags.
- Click "Post".
Hopefully that will provide some additional information about the problem.
https://downloads.arduino.cc/packages/package_index.json file signature verification failed. File ignored.
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
https://downloads.arduino.cc/packages/package_index.json file signature verification failed. File ignored.
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
https://downloads.arduino.cc/packages/package_index.json file signature verification failed. File ignored.
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=bossac version=1.8.0-48-gb176eee packager=arduino
Index error: could not find referenced tool name=openocd version=0.9.0-arduino packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS-Atmel version=1.2.0 packager=arduino
OK, that information was indeed helpful. I have a troubleshooting guide I would like you to follow:
Step A
- (In the Arduino IDE) File > Preferences
- Click the link at the line following "More preferences can be edited directly in the file". This will open the Arduino15 (or similar name depending on OS) folder.
- Delete all files in that folder except for preferences.txt. Please be very careful when deleting things on your computer. When in doubt, back up!
- (In the Arduino IDE) Close the Boards Manager window if it's open.
- Tools > Board > Boards Manager
- Wait for the downloads to finish.
Does the "file signature verification failed" error still occur?
No
It was likely caused by a temporary glitch in the Arduino IDE and should now be fixed.
Yes
Go on to the next step:
Step B
- Close all Arduino IDE windows.
- If using Windows, download the "Windows ZIP file for non admin install" version of the Arduino IDE from the Software page. Unzip the downloaded file to any convenient location on your computer where you have write access. Don't put it under C:\Program Files or C:\Program Files (x86) because Windows 10 places extra restrictions on those folders.
- Create a folder named portable in the Arduino IDE installation folder to set the Arduino IDE into portable mode. If you are using macOS, you can follow these instructions.
- Start the Arduino IDE.
- Tools > Board > Boards Manager
- Wait for the downloads to finish.
Does the "file signature verification failed" error still occur?
No
It may have been caused by your antivirus software being more restrictive of the location of the Arduino15 folder. You may be able to fix the issue by adjusting your antivirus software's settings.
Yes
Go on to the next step:
Step C
- TEMPORARILY disable your antivirus software.
- (In the Arduino IDE) Close the Boards Manager window if it's open.
- Tools > Board > Boards Manager
- Wait for the downloads to finish.
- Re-enable your antivirus software immediately.
Does the "file signature verification failed" error still occur?
No
You'll need to whitelist the appropriate folder, file, or process in your antivirus software's settings.
Yes
Go on to the next step:
Step D
- Connect to the Internet through a different network. If you're currently using the network at your work, try your home network. You can try connecting via the WiFi hotspot on your phone.
- (In the Arduino IDE) Close the Boards Manager window if it's open.
- Tools > Board > Boards Manager
- Wait for the downloads to finish.
Does the "file signature verification failed" error still occur?
No
The issue may be caused by the firewall on the original network.
Yes
Go on to the next step:
Step E
- Open a new browser tab or window.
- Press F12 to open the toolbox.
- Click the "Network" tab of the toolbox.
- On the next bar down in the toolbox, click "All".
- Check the box next to "Disable cache".
- Paste the URL (https://downloads.arduino.cc/packages/package_index.json or https://downloads.arduino.cc/packages/package_index.json.sig) into the URL bar of your browser.
- Press Enter.
- In the toolbox, click on the line that says "package_index.json" or "package_index.json.sig" (depending on which URL you're currently getting the headers for).
- In the pane that appears, click the "Headers" tab.
- If using Firefox, switch the "Raw headers" switch to the on position for the "Response headers" section.
- Click and drag to select all text in the "Response headers" section.
- Press Ctrl + C to copy the selected text to the clipboard.
- You can now either paste the copied header text directly into a reply on this issue report or save it in a .txt file and attach the .txt file in a reply there.
- (For package_index.json) In the browser window where you have the package_index file open, press Ctrl + S
- Save the file as package_index.json.txt
- Attach the saved file to your reply in the issue report. In the case of package_index.json.sig, the browser shouls have downloaded the file automatically, but you'll need to rename the file to package_index.json.sig.txt so that GitHub will allow you to attach the file.
- Repeat the process for the other URL.
The information from step E will be used by one of the Arduino developers to investigate the issue and hopefully get it fixed soon. Thanks!
I tried all of that, and i still get the same message. I have attached the two files for step E
Arduino headers.txt (1.57 KB)
package_index.json.txt (256 KB)
Thanks! We also need you to provide the headers and file from:
https://downloads.arduino.cc/packages/package_index.json.sig
Just follow step E over again, but with that URL instead.
Also, please post these to the issue report here:
so that Arduino's developer in charge of the investigation will see them.
ok. I just read the link above about the bug. I live in Australia, and the bug reports that the issue is in this part of the world. Damn
Yes. It's a very unfortunate situation but Arduino has a very knowledgeable person working on getting it fixed so I'm sure it will be resolved soon. The tricky thing is that nobody from Arduino is able to reproduce the issue so we're relying on the affected users to provide the necessary information.
Until the problem is fixed, the workaround is to use the Arduino Web Editor: