sampling error; sampling not done (other similar issue solutions not working)

Hi,

I am running into sampling errors when trying to run a brms model. Based on other issues (from which the solutions have unfortunately not worked for me) and the error message, it seems to be going wrong with calling the sampler.

I am quite new to rstan (and I am not really familiar with Stan code), so any help would be much appreciated! Thanks a lot in advance.

I get the following error with each of the chains of the brms model:
[1] "Error in sampler$call_sampler(args_list[[i]]) : "
[2] " c++ exception (unknown reason)"
error occurred during calling the sampler; sampling not done

This is the model I am trying to run:
cor_mod <- brm(Correct_emo ~ f_group + f_percentage + f_emotion + f_groupf_percentagef_emotion + (1 + f_emotion | f_ppn) + (1 + f_emotion | f_group), data = comb2, family = 'bernoulli', warmup = 1000, iter = 6000, chains = 4, cores = 6, control = list(adapt_delta = 0.95))

The model compiles very quickly, but then this error comes up right after. The model does run without the random slopes.

output of rstan:::get_CXX(): clang++

I have multiple MakeVars files so I am not quite sure which one is relevant (also one file that is named old_makevars.rd).

sessionInfo()
R version 3.6.0 (2019-04-26)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS 10.15

Matrix products: default
BLAS: /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRlapack.dylib

locale:
[1] en_AU.UTF-8/en_AU.UTF-8/en_AU.UTF-8/C/en_AU.UTF-8/en_AU.UTF-8

attached base packages:
[1] stats graphics grDevices utils datasets methods base

other attached packages:
[1] foreign_0.8-72 brms_2.10.3 Rcpp_1.0.2 rstan_2.19.2 ggplot2_3.2.1 StanHeaders_2.19.0

loaded via a namespace (and not attached):
[1] Brobdingnag_1.2-6 pkgload_1.0.2 gtools_3.8.1 threejs_0.3.1 shiny_1.4.0
[6] assertthat_0.2.1 stats4_3.6.0 remotes_2.1.0 sessioninfo_1.1.1 pillar_1.4.2
[11] backports_1.1.5 lattice_0.20-38 glue_1.3.1 digest_0.6.22 promises_1.1.0
[16] colorspace_1.4-1 htmltools_0.4.0 httpuv_1.5.2 Matrix_1.2-17 plyr_1.8.4
[21] dygraphs_1.1.1.6 pkgconfig_2.0.3 devtools_2.2.1 purrr_0.3.3 xtable_1.8-4
[26] scales_1.0.0 processx_3.4.1 later_1.0.0 tibble_2.1.3 bayesplot_1.7.0
[31] usethis_1.5.1 ellipsis_0.3.0 DT_0.9 shinyjs_1.0 withr_2.1.2
[36] lazyeval_0.2.2 cli_1.1.0 magrittr_1.5 crayon_1.3.4 mime_0.7
[41] memoise_1.1.0 ps_1.3.0 fs_1.3.1 nlme_3.1-139 xts_0.11-2
[46] pkgbuild_1.0.6 colourpicker_1.0 rsconnect_0.8.15 tools_3.6.0 loo_2.1.0
[51] prettyunits_1.0.2 matrixStats_0.55.0 stringr_1.4.0 munsell_0.5.0 callr_3.3.2
[56] compiler_3.6.0 rlang_0.4.1 grid_3.6.0 ggridges_0.5.1 htmlwidgets_1.5.1
[61] miniUI_0.1.1.1 crosstalk_1.0.0 igraph_1.2.4.1 base64enc_0.1-3 testthat_2.2.1
[66] codetools_0.2-16 gtable_0.3.0 inline_0.3.15 abind_1.4-5 curl_4.2
[71] reshape2_1.4.3 markdown_1.1 R6_2.4.0 gridExtra_2.3 rstantools_2.0.0
[76] zoo_1.8-6 bridgesampling_0.7-2 dplyr_0.8.3 fastmap_1.0.1 shinythemes_1.1.2
[81] shinystan_2.5.0 rprojroot_1.3-2 desc_1.2.0 stringi_1.4.3 parallel_3.6.0
[86] tidyselect_0.2.5 coda_0.19-3

Start by reproducing the brm model with and without the random slopes, using the reported RStan, brms, R, and macOS versions. Inspect the sampler call and compare rstan:::get_CXX() and the relevant MakeVars configuration. Done means identifying whether the failure is caused by the model or the local compilation/runtime setup and documenting a reproducible resolution.