Friction is defined as the difference between military theory and reality in the book On War.

There are plenty of such frictions in software development, for example:

• API's that does work quite as you though it did, or it changed
• Bugs. Security alerts. A breaking dependency upgrade.
• Someone gets sick and information is lost.
• Requirements are unclear, or a client changes what they want, during of after development.
• Laptop breaks or gets stolen.
• Tooling breaks.

How to avoid that?

• smaller scopes and shorter iterations
• more autonomy
• redundancy
• better planning
• automation
• experience
• gaming
• checklists and runbooks