Since upgrading to 1.8.1, Octoprint refuses to connect to printer (BTT SKR 1.4 Turbo board). Connection is achieved via UART on Raspberry Pi 3B+ at 250000 baud. This connection has been working prior to the upgrade.
Terminal window in safe mode indicates that a SerialException is being generated when opening the port with the exception string 'Invalid Argument', which appears to be due to the speed selected. Changing to 230400 prevents the SerialException, but does not connect to the printer due to mismatched baudrate. Attempts to change the internal UART assignment with dtoverlay=pi3-miniuart-bt did not resolve this, although ttyAMA0 does not raise the SerialException for 250000.
The pyserial documentation does not include the 250000 baud rate, and I'm suspicious that an update to either the pyserial library or an underlying component of the system no longer permits the use of this speed, or at least not via this UART.
I would prefer to avoid using the USB connection or moving to a Pi 4 due to having the boards mounted in a box inside the printer without access to the USB port on the mainboard. I suspect that this will require a rebuild of Marlin to use a different baudrate, but if anybody has any other advice or alternatives I would love to hear them.