[R-sig-ME] glmer / MuMin : Error in asMethod(object) : not a positive definite matrix

Guillaume Adeux gu|||@ume@|mon@@2 @end|ng |rom gm@||@com
Fri Aug 28 14:40:24 CEST 2020

Hello everyone,

I am currently exploring the relationship between weed biomass during the
fallow period and cover crop productivity (in interaction with tillage
type, nitrogen fertilization, and cover crop species, as imposed by the
3-way factorial experimental design).
This results in a highly complex model which I wish to reduce to achieve
Hence, I fitted the full model with glmer as:


and fed it to MuMin::dredge() as:

options(na.action = "na.fail")

However, I am unable to retrieve my "dred_CC" (after 8 days, arf) object
because dredge() stops after returning:
*Error in asMethod(object) : not a positive definite matrix*
Is this due to a specific problem with one given model? If that's the case,
how can I tell the function to simply skip it?
To be completely transparent, it also states "In addition: There were 50 or
more warnings (use warnings() to see the first 50)" but I don't believe the
problem comes from there.

I would greatly greatly appreciate it if someone could lend a hand.
Thanks for your time.

Guillaume ADEUX

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