X_TELEMETRY_SAMPLER_ARG_INVALID

the trace sampling ratio is not a number between 0 and 1

OTEL_TRACES_SAMPLER_ARG holding a value outside [0, 1], or one that is not a number. Read at the first span, not at boot — so it warns through the logger and samples every trace rather than killing a process mid-request over a sampling typo. Losing the traces silently is the worse failure; the bill is the loud one

set OTEL_TRACES_SAMPLER_ARG=0.05 — the cause names the spelling it read