Hi, to complete this: the issue at @Tomas-sailing his boat has been solved and tracked down to be remnants of earlier experiments with SignalK and Node-RED.
They filled up the data partition right down to the last byte.
Solution is to empty the data partition, and the various options for that are explained here:
Ps. per v3.60c where the alarm was introduced, there is also a new page in the menu, showing how much free space there is left exactly; as well as other details: