# Unsure why data is filtering out

**URL:** <https://nextstrain.discourse.group/t/unsure-why-data-is-filtering-out/453>\
**Category:** Help and Getting Started\
**Created:** [March 25, 2021, 1:34pm UTC](https://nextstrain.discourse.group/t/unsure-why-data-is-filtering-out/453 "2021-03-25T13:34:43Z")\
**Posts on this page:** 1\
**Showing post:** 4

<div class="post-metadata">

**Author:** ![jlhudd](https://yyz1.discourse-cdn.com/flex031/user_avatar/nextstrain.discourse.group/jlhudd/32/583_2.png) [@jlhudd](https://nextstrain.discourse.group/u/jlhudd)\
**Post date:** [March 30, 2021, 6:25pm UTC](https://nextstrain.discourse.group/t/unsure-why-data-is-filtering-out/453/4 "2021-03-30T18:25:58Z")

</div>

Hi @l.hughes, this error is caused when mafft tries to use more memory than is available on your machine and its process gets killed. We think this issue is caused by a memory leak in mafft. The best workaround for now is to switch from mafft to our nextalign tool. @rneher has written [a guide for making this switch to nextalign](https://nextstrain.discourse.group/t/avoiding-large-memory-requirements-by-switching-to-nextalign/447).

Would you be willing to try out this alternate approach and let us know how it works for you?

---

_[View the full topic](https://nextstrain.discourse.group/t/unsure-why-data-is-filtering-out/453)._