# Input form error code

**URL:** https://ask.bioexcel.eu/t/input-form-error-code/4939
**Category:** HADDOCK
**Created:** [April 24, 2024, 4:18pm UTC](https://ask.bioexcel.eu/t/input-form-error-code/4939 "2024-04-24T16:18:53Z")
**Posts on this page:** 1
**Showing post:** 2

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### Author: ![VGPReys](https://dub1.discourse-cdn.com/flex013/user_avatar/ask.bioexcel.eu/vgpreys/32/960_2.png) [@VGPReys](https://ask.bioexcel.eu/u/VGPReys)
#### Post date: [April 25, 2024, 6:56am UTC](https://ask.bioexcel.eu/t/input-form-error-code/4939/2 "2024-04-25T06:56:26Z")

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Dear Mercedes,

Thanks for your interest in using HADDOCK for your research.

First of all, are Calcium ions important for your docking ? if not, you can remove them using the `pdb_striphet` function from [pdb\_tools](https://wenmr.science.uu.nl/pdbtools/) to remove all HETATM in your pdb, which is often a good idea.

If they are important, you could try using python regular expression library ( `re` ) to match your case and modify it accordingly.  
Also, the `sed` command in bash can do this trick.

Finally, check these two related bioexcel posts: [1](https://ask.bioexcel.eu/t/error-elemental-ion-ca-without-specified-charge/347/4), [2](https://ask.bioexcel.eu/t/pdb-file-elemental-ion-ca-without-specified-charge/3443/2)

With the hope that this answer will help you.  
Cheers

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