# InVEST NDR model error : UFuncTypeError: ufunc 'subtract' did not contain a loop with signature matching types

**URL:** https://community.naturalcapitalalliance.org/t/invest-ndr-model-error-ufunctypeerror-ufunc-subtract-did-not-contain-a-loop-with-signature-matching-types/1045
**Category:** Software Support
**Tags:** ndr
**Created:** [June 9, 2020, 8:30am UTC](https://community.naturalcapitalalliance.org/t/invest-ndr-model-error-ufunctypeerror-ufunc-subtract-did-not-contain-a-loop-with-signature-matching-types/1045 "2020-06-09T08:30:43Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![luisagalgani](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.naturalcapitalalliance.org/luisagalgani/32/777_2.png) [@luisagalgani](https://community.naturalcapitalalliance.org/u/luisagalgani)
#### Post date: [June 9, 2020, 8:30am UTC](https://community.naturalcapitalalliance.org/t/invest-ndr-model-error-ufunctypeerror-ufunc-subtract-did-not-contain-a-loop-with-signature-matching-types/1045/1 "2020-06-09T08:30:43Z")

</div>

Hello, I am trying to run the NDR model but I keep getting this error  
UFuncTypeError: ufunc ‘subtract’ did not contain a loop with signature matching types (dtype(’\<U3’), dtype(’\<U3’)) -\> dtype(’\<U3’)  
I do obtain some intermediate files thoug. Any idea? Many many thanks, help really appreciated! Here’s the log:

[InVEST-Nutrient-Delivery-Ratio-Model-(NDR)-log-2020-06-09–10\_21\_05.txt](https://community.naturalcapitalalliance.org/uploads/short-url/lWhHRpGYpuEmncU6J9HH2lFdWO0.txt) (3.4 KB)

---

<div class="post-metadata">

### Author: ![jdouglass](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.naturalcapitalalliance.org/jdouglass/32/9_2.png) [@jdouglass](https://community.naturalcapitalalliance.org/u/jdouglass)
#### Post date: [June 9, 2020, 10:08pm UTC](https://community.naturalcapitalalliance.org/t/invest-ndr-model-error-ufunctypeerror-ufunc-subtract-did-not-contain-a-loop-with-signature-matching-types/1045/2 "2020-06-09T22:08:46Z")

</div>

Now _that_ is a cryptic error message! After a little digging, could you check to make sure that the `"proportion_subsurface_n"` column in your biophysical table has numeric values? If it looks like they do, could you attach your CSV here so we can take a look?

Thanks!  
James

---

<div class="post-metadata">

### Author: ![luisagalgani](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.naturalcapitalalliance.org/luisagalgani/32/777_2.png) [@luisagalgani](https://community.naturalcapitalalliance.org/u/luisagalgani)
#### Post date: [June 10, 2020, 6:31am UTC](https://community.naturalcapitalalliance.org/t/invest-ndr-model-error-ufunctypeerror-ufunc-subtract-did-not-contain-a-loop-with-signature-matching-types/1045/3 "2020-06-10T06:31:58Z")

</div>

Hello James, many thanks for your prompt reply. The problem was right the “proportion\_subsurface\_n” column. I had that empty. By filling it with 0 the model could then run successfully. Many thanks indeed, really happy that worked! Have a nice day, Luisa