Troubleshooting

The compile server cannot be reached

Message: The compile server is not running…, Cannot connect to the compile server, or The server is busy.

On Circzy online (creator.circzy.com):

• Check your internet connection, then press ▶ again.
• If the server is busy, wait a moment. Pro and Classroom users get a priority queue.
• If the problem lasts more than a few minutes, the server may be under maintenance. Contact the Circzy admin.

On the offline version:

• Check that the Circzy Server window is open. If you closed it, run start.bat again.
• If the window shows an error, read the last lines. A missing Node.js installation or a port that is already in use (3001) are the usual causes.

The board package is not installed (offline version)

Message: The package for this board is not installed on this computer…

Close both Circzy windows, run setup.bat again (only missing packages are downloaded), then run start.bat. If the ESP32 package keeps failing, move the folder to a short path such as E:\circzy and try again.

The disk is full (offline version)

Message: The computer disk is full… or ENOSPC: no space left on device.

Free a few GB on the drive that holds the Circzy folder. While Circzy is closed, you can safely delete tools\build and tools\arduino-data\staging. The server also removes unused build folders every time it starts.

Compilation fails

The Compilation Error panel shows the compiler message with the line number in sketch.ino:

• 'x' was not declared in this scope: a misspelled name or a missing #include.
• expected ';' before …: a missing semicolon on the line before.
• No such file or directory for a .h file: install the library in the Library Manager.

The first compile is slow

The first compile of each board fills the cache, and ESP32 can take 30–60 seconds. Later compiles take a few seconds. On the offline version, the server also warms up every board for 1–3 minutes right after start.bat.

Nothing happens in the circuit

• Check the wiring against the part's wiring hint, shown in the hint bar at the bottom of the canvas when the part is selected, or in the Parts Reference. Power (VCC, VDD, 5V, 3V3) and GND must be connected.
• Make sure the pin in your code matches the pin you wired. On ESP32 use GPIO numbers; on ESP8266 D1 is GPIO 5.
• LEDs need the anode (A) towards the pin and the cathode (C) towards GND.
• I²C displays must be on the board's I²C pins: A4/A5 on Uno and Nano, 20/21 on Mega, GPIO 21/22 on ESP32, D2/D1 on ESP8266, GP4/GP5 on Pico, PB7/PB6 on Blue Pill.

A button always reads the same value

Use INPUT_PULLUP and connect the button between the pin and GND, or add a pull-down resistor. A floating input has no defined value.

The simulation runs slower than real time

Loops without delay() keep the emulator busy. Add a short delay() where it does not change your program, close other heavy browser tabs, or use a faster computer. See Simulation Limits.

My projects disappeared

• Make sure you are signed in with the same Google account. Account projects are only visible to their owner.
• Projects created without signing in are stored per browser and per address. Make sure you use the same browser and address. Private windows do not keep projects.
• Import your .circzy.json backups if needed.