Support for Robotic Vacuum cleaners

My robotic vacuum cleaner shows error E40 or E42

My robotic vacuum cleaner shows error E21, warning triangle and Play button are blinking

My robotic vacuum cleaner shows error code E17

Will the clock settings be saved after exchanging batteries or when the robotic vacuum cleaner was not charged for a longer time period?

Will I need to use another vacuum cleaner apart from the robotic vacuum?

Where can I buy accessories (filters, brushes, battery packs, spare parts) for my robotic vacuum?

When to change the robotic vacuum's batteries

What is the maximum carpet thickness on which to use the automatic vacuum cleaner?

What happens if a (new) obstacle gets in the area already mapped by the robotic vacuum?

What can I do if the robotic vacuum wheel(s) is stopped?