Zero-Inflation NB - object 'model_count' not found

Question

I am modeling a mediated zero-inflated negative binomial (ZINB) model. i am following the steps of O'Rourke & Vazquez (2019) --> https://www.sciencedirect.com/science/article/abs/pii/S0306460319301078

A few days ago i was running a different ZINB model which ran perfectly fine. However, today i wrote a different model, same variables, but somehow it doesn't run anymore and gives a strange error. When i try my previous model i suddenly get the same error, namely:

Error in zeroinfl(Y1 ~ X1 + M1 | X1 +  : object 'model_count' not found

The rest of my code:

#loading required packages
library(psych)
library(foreign)
library(ggplot2)
library(MASS)
library(pscl)
library(nonnest2)
library(lmtest)
library(boot)

#Import data
mydata

#Fit a ZINB model
ex1zinb <- zeroinfl(X1 ~ Y1 + M1 | Y1 + M1, data = mydata, dist="negbin", EM= TRUE)

I already checked the assumption for the statistical analyses etc., and it is especially strange that a similar model did run a few days ago and not anymore. I did try to install several packages today but i ran into a non-zero exit status. Following some comments on stackoverflow i installed a package by adding dependencies = TRUE, but it ran stuck. Afterwards the problems started. Maybe there is something wrong with my packages?

When loading the libraries i get the following messages:

> library(psych)
> library(foreign)
> library(ggplot2)
Need help? Try Stackoverflow: https://stackoverflow.com/tags/ggplot2

Attaching package: ‘ggplot2’

The following objects are masked from ‘package:psych’:

    %+%, alpha

> library(MASS)
> library(pscl)
Classes and Methods for R developed in the
Political Science Computational Laboratory
Department of Political Science
Stanford University
Simon Jackman
hurdle and zeroinfl functions by Achim Zeileis
> library(nonnest2)
This is nonnest2 0.5-3.
nonnest2 has not been tested with all combinations of model classes.
> library(lmtest)
Loading required package: zoo

Attaching package: ‘zoo’

The following objects are masked from ‘package:base’:

    as.Date, as.Date.numeric

> library(boot)

Attaching package: ‘boot’

The following object is masked from ‘package:psych’:

    logit

Anyone some suggestions/insights? Thanks in advance!

Edit: i do get a normal output when running a non-zero inflated negative binomial model. The following code runs smooth:

summary(ex1nb <- glm.nb(Y1~ X1 + M1, data = mydata))

So i think my data is fine?

Answer 1

I got that error too. I used R 4.0 then tried R 3.6. No luck.

I was able to get the error to go away when I removed the EM = TRUE parameter.

I'm not sure if this helps.