I have been getting this error for the first time for commands that used to run well before:
# conversion from char to numeric:
as.numeric(df$col) -> df$col
Error: (converted from warning) NAs introduced by coercion
# running metafor
rma(yi, vi, data=r1s2)
Error: (converted from warning) Studies with NAs omitted from model fitting.
The issue must be with the R environment as these commands are running perfectly on a different computer. The only wrong I can think of is installing a package from GitHub or updating R a few hours ago. The only relevant answer I've found so far is also not working:
Sys.setenv(R_REMOTES_NO_ERRORS_FROM_WARNINGS="true")