# Error while running GATK4 mutect2

**URL:** <https://help.galaxyproject.org/t/error-while-running-gatk4-mutect2/6557>\
**Category:** usegalaxy.org support\
**Tags:** gatk4\
**Created:** [August 21, 2021, 10:25am UTC](https://help.galaxyproject.org/t/error-while-running-gatk4-mutect2/6557 "2021-08-21T10:25:45Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ambarisha\_samantaray](https://avatars.discourse-cdn.com/v4/letter/a/c6cbf5/32.png) [@ambarisha\_samantaray](https://help.galaxyproject.org/u/ambarisha_samantaray)\
**Post date:** [August 21, 2021, 10:25am UTC](https://help.galaxyproject.org/t/error-while-running-gatk4-mutect2/6557/1 "2021-08-21T10:25:45Z")

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My variant calling jobs are giving errors. I am posting the error messages as snaps. Can someone please help me out with the problem?

 ![IMG_20210821_155210](https://us1.discourse-cdn.com/flex020/uploads/galaxy/original/2X/7/7b85506c91a2e890c73e0d6399fdc829271f94aa.jpeg)  
 ![IMG_20210821_154932](https://us1.discourse-cdn.com/flex020/uploads/galaxy/original/2X/b/bc638846bb97b5ec97ccaa4062d8bd1d3f5dece6.jpeg)

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**Author:** ![jennaj](https://sea2.discourse-cdn.com/flex020/user_avatar/help.galaxyproject.org/jennaj/32/27_2.png) [@jennaj](https://help.galaxyproject.org/u/jennaj)\
**Post date:** [August 23, 2021, 4:56pm UTC](https://help.galaxyproject.org/t/error-while-running-gatk4-mutect2/6557/2 "2021-08-23T16:56:33Z")

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Hello,

The tool is expecting a tag that is not present in the input `BAM` dataset. Specifically, the “sample” attribute.

This information can be added when mapping (read group options) or adjusted after mapping with a tool like `AddOrReplaceReadGroups add or replaces read group information`.

More help:

- Search the `BAM` format specification PDF with the keyword “sample” to learn more about the attribute: [https://samtools.github.io/hts-specs/SAMv1.pdf](https://samtools.github.io/hts-specs/SAMv1.pdf)  
\*`GATK4` workflow documentation may also help: [https://gatk.broadinstitute.org/hc/en-us](https://gatk.broadinstitute.org/hc/en-us)
- The tool form itself has additional usage/formatting help.
- Tutorials: [Galaxy Training!](https://training.galaxyproject.org/training-material/topics/variant-analysis/)