Various error messages displayed by the IDE contain these URLs which do not point to meaningful resources anymore:

• http://www.arduino.cc/en/guide/troubleshooting#upload
• http://www.arduino.cc/en/guide/troubleshooting#size

They should be replaced with:

• https://support.arduino.cc/hc/en-us/articles/4403365313810
• https://support.arduino.cc/hc/en-us/articles/360013825179

This was partially done in #11387 but there are still many occurrences in the code base.