What you see
Connection diagnostics show “No serial permission” or “Web Serial unavailable”, or the browser blocks the port picker.
Likely causes
- The browser does not expose Web Serial, or the site is outside a permitted secure context.
- School policy restricts serial access or the USB bridge/device.
- The operating system has not recognized the board or required USB interface.
Diagnostic steps
Record the non-sensitive environment
Note browser/OS version, Circuitera origin, board family and whether a known data cable works elsewhere. Do not share account tokens, private code or serial contents.
Separate site permission from device policy
A user permission prompt and an administrator policy are different controls. Signing in to Circuitera or changing a sketch cannot override a managed serial policy.
Ask IT to check the actual device path
Have the administrator review site access, browser storage/download rules, serial-device policy and host recognition for the exact board/bridge. Give the symptom rather than assuming every failure is a blocked site.
Continue a simulator-only lesson
Launch a supported Uno tutorial, press Run and inspect its modeled output. Export the sketch so it can be uploaded later from an approved setup.
Board-specific notes
Uno/Nano use their USB-to-serial bridge. Mega’s extra UARTs are not separate browser ports. Leonardo/Micro native USB may re-enumerate during reset. Pro Mini requires an external adapter with the correct logic voltage.
Safe recovery
Use the approved school process for policy changes. Circuitera does not bypass device management or filters, and an offline cache does not grant USB permission.
Evidence and references
Reviewed 2026-10-23 against Circuitera’s actual behavior. An editorial review is separate from a physical board test.
Circuitera implementation evidence
src/connectionDiagnostics.js; src/App.jsx: serialBlocked/connectBoard