The degree must be less than or equal to the correction factor？

Library Questions
1

I reduced the modulus to 40, but there was an error on the other side at line 53: EvalBootstrap(): The degree [20] must be less than or equal to the correction factor [9]

CCParams parameters;
SecretKeyDist secretKeyDist = SPARSE_TERNARY;
parameters.SetSecretKeyDist(secretKeyDist);
parameters.SetSecurityLevel(HEStd_128_classic);
parameters.SetNumLargeDigits(3);
parameters.SetKeySwitchTechnique(HYBRID);
ScalingTechnique rescaleTech = FIXEDAUTO;
parameters.SetScalingModSize(40);
parameters.SetScalingTechnique(rescaleTech);
std::vector<uint32_t> levelBudget = {2, 2};
std::vector<uint32_t> bsgsDim = {0, 0};
uint32_t levelsAvailableAfterBootstrap = 8;
usint depth =levelsAvailableAfterBootstrap + FHECKKSRNS::GetBootstrapDepth(levelBudget, secretKeyDist);
parameters.SetMultiplicativeDepth(depth);

2

The ratio between the first modulus and scaling factor (scaling modulus) should be relatively small (not more than 10 bits in logarithmic scale). The default value of first modulus is 60. I suggest reducing it to 50 or even lower.