# Error with horseshoe priors
**URL:** https://discourse.mc-stan.org/t/error-with-horseshoe-priors/32538
**Category:** General
**Tags:** brms
**Created:** [August 24, 2023, 11:11am UTC](https://discourse.mc-stan.org/t/error-with-horseshoe-priors/32538 "2023-08-24T11:11:10Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@HenriW](https://discourse.mc-stan.org/u/HenriW)
#### Post date: [August 24, 2023, 11:11am UTC](https://discourse.mc-stan.org/t/error-with-horseshoe-priors/32538/1 "2023-08-24T11:11:11Z")
I’m running into a fairly confusing issue with brms and horseshoe -priors. Models fit nicely, I can get the basic outputs and summaries, but trying to work with the model object with functions such as loo(), pp\_check(), conditional\_effects() or tools from emmeans or marginaleffects -packages produce an error:
```plaintext
Error in if (special$name == "horseshoe") { : argument is of length zero
```
The thing is that the issue doesn’t appear with all models using horseshoe -priors I’m running. I’m quite a bit clueless of what the error actually means and how should I start debugging the whole issue?
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### Author:  [@maxbiostat](https://discourse.mc-stan.org/u/maxbiostat)
#### Post date: [August 24, 2023, 11:18am UTC](https://discourse.mc-stan.org/t/error-with-horseshoe-priors/32538/2 "2023-08-24T11:18:40Z")
@paul.buerkner
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### Author:  [@paul.buerkner](https://discourse.mc-stan.org/u/paul.buerkner)
#### Post date: [August 24, 2023, 11:43am UTC](https://discourse.mc-stan.org/t/error-with-horseshoe-priors/32538/3 "2023-08-24T11:43:39Z")
Can you please provide a minimial reproducible example?