In case you missed it, the big news is that a minimal Arduino core is up and working on the ESP32. There’s still lots left to do, but the core functionality — GPIO, UART, SPI, I2C, and … ...

Did I miss something or is there a dependency (another library containing the missing file) to be installed? If I revert to version 1.5.6, the error message does not show up.

Arduino installation Arduino Library manager: Go to sketch -> Include Library -> Manage Libraries, search for NimBLE and install. Alternatively: Download as .zip and extract to Arduino/libraries ...

But thanks to the rtl_433_ESP Arduino library developed by [NorthernMan54], we’re now able to pack that functionality into a much smaller package.