Initialization failed; Assertion on 'files' failed: No file provided

I can’t find an example of exactly this problem anywhere, and I am really struggling with it! This morning the models compiled, this afternoon they don’t. This is using cmdstan as the backend, with latest version of brms and cmdstan, on Windows 10.

Here is the error that these formerly-working models produce now after an installation step:

Start sampling
Chain 1 Initialization failed.
Chain 3 Initialization failed.
Chain 2 Initialization failed.
Chain 4 Initialization failed.
Error in cmdstanr::read_cmdstan_csv(out$output_files(), variables = "",  : 
  Assertion on 'files' failed: No file provided.
In addition: Warning message:
No chains finished successfully. Unable to retrieve the fit. 

Frustratingly, the demo models from brms documentation DO work (at least those I tried did). So I’m at a loss – is it something in my particular model that’s the problem?

session info

R version 4.3.0 (2023-04-21 ucrt)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 19045)

Matrix products: default

[1] LC_COLLATE=English_Canada.utf8  LC_CTYPE=English_Canada.utf8    LC_MONETARY=English_Canada.utf8 LC_NUMERIC=C                   
[5] LC_TIME=English_Canada.utf8    

time zone: America/Toronto
tzcode source: internal

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

other attached packages:
 [1] tidybayes_3.0.4 lubridate_1.9.2 forcats_1.0.0   stringr_1.5.0   dplyr_1.1.2     purrr_1.0.1     readr_2.1.4     tidyr_1.3.0    
 [9] tibble_3.2.1    ggplot2_3.4.2   tidyverse_2.0.0 brms_2.19.6     Rcpp_1.0.10    

loaded via a namespace (and not attached):
  [1] gridExtra_2.3        inline_0.3.19        rlang_1.1.1          magrittr_2.0.3       furrr_0.3.1          matrixStats_1.0.0   
  [7] compiler_4.3.0       loo_2.6.0            callr_3.7.3          vctrs_0.6.2          reshape2_1.4.4       pkgconfig_2.0.3     
 [13] arrayhelpers_1.1-0   crayon_1.5.2         fastmap_1.1.1        backports_1.4.1      ellipsis_0.3.2       utf8_1.2.3          
 [19] cmdstanr_0.5.3       threejs_0.3.3        promises_1.2.0.1     markdown_1.7         tzdb_0.4.0           ps_1.7.5            
 [25] bit_4.0.5            xfun_0.39            jsonlite_1.8.5       later_1.3.1          broom_1.0.5          parallel_4.3.0      
 [31] prettyunits_1.1.1    R6_2.5.1             dygraphs_1.1.1.6     stringi_1.7.12       StanHeaders_2.26.26  parallelly_1.36.0   
 [37] rstan_2.21.8         job_0.3.0            knitr_1.43           modelr_0.1.11        zoo_1.8-12           base64enc_0.1-3     
 [43] bayesplot_1.10.0     splines_4.3.0        httpuv_1.6.11        Matrix_1.5-4         igraph_1.4.3         timechange_0.2.0    
 [49] tidyselect_1.2.0     rstudioapi_0.14      abind_1.4-5          codetools_0.2-19     miniUI_0.1.1.1       processx_3.8.1      
 [55] listenv_0.9.0        pkgbuild_1.4.0       lattice_0.21-8       plyr_1.8.8           shiny_1.7.4          withr_2.5.0         
 [61] bridgesampling_1.1-2 posterior_1.4.1      coda_0.19-4          future_1.32.0        RcppParallel_5.1.7   ggdist_3.3.0        
 [67] xts_0.13.1           pillar_1.9.0         tensorA_0.36.2       checkmate_2.2.0      DT_0.28              stats4_4.3.0        
 [73] shinyjs_2.1.0        distributional_0.3.2 generics_0.1.3       vroom_1.6.3          rprojroot_2.0.3      hms_1.1.3           
 [79] rstantools_2.3.1     munsell_0.5.0        scales_1.2.1         globals_0.16.2       gtools_3.9.4         xtable_1.8-4        
 [85] glue_1.6.2           tools_4.3.0          shinystan_2.6.0      data.table_1.14.8    colourpicker_1.2.0   mvtnorm_1.2-2       
 [91] grid_4.3.0           ape_5.7-1            crosstalk_1.2.0      colorspace_2.1-0     nlme_3.1-162         cli_3.6.1           
 [97] fansi_1.0.4          svUnit_1.0.6         Brobdingnag_1.2-9    gtable_0.3.3         broom.mixed_0.2.9.4  digest_0.6.31       
[103] htmlwidgets_1.6.2    farver_2.1.1         htmltools_0.5.5      lifecycle_1.0.3      here_1.0.1           mime_0.12           
[109] bit64_4.0.5          shinythemes_1.2.0   

It seems like this happens with brms and the cmdstanr backend, but not the rstan backend.