# Troubleshooting for an error in Galaxy Training Materials "reference based RNA seq data analysis"

**URL:** <https://help.galaxyproject.org/t/troubleshooting-for-an-error-in-galaxy-training-materials-reference-based-rna-seq-data-analysis/16443>\
**Category:** usegalaxy.org.au support\
**Tags:** mapping\
**Created:** [October 29, 2025, 7:28am UTC](https://help.galaxyproject.org/t/troubleshooting-for-an-error-in-galaxy-training-materials-reference-based-rna-seq-data-analysis/16443 "2025-10-29T07:28:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![musfira](https://avatars.discourse-cdn.com/v4/letter/m/ee59a6/32.png) [@musfira](https://help.galaxyproject.org/u/musfira)\
**Post date:** [October 29, 2025, 7:28am UTC](https://help.galaxyproject.org/t/troubleshooting-for-an-error-in-galaxy-training-materials-reference-based-rna-seq-data-analysis/16443/1 "2025-10-29T07:28:03Z")

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I have been following the tutorial for **“Reference-based RNA-seq Data Analysis”** from Galaxy Training Materials. While performing the mapping step, I encountered the following error when selecting tool parameters:  
**“No dataset pair dataset collections with fastqsanger, fastqsanger.gz, fastqsanger.bz2, or fasta elements available.”**

I have already checked the attributes of the input files, and both are in the correct format ( **fastqsanger** ). Could someone please help me resolve this issue? Thank you.

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**Author:** ![wm75](https://sea2.discourse-cdn.com/flex020/user_avatar/help.galaxyproject.org/wm75/32/56_2.png) [@wm75](https://help.galaxyproject.org/u/wm75)\
**Post date:** [October 29, 2025, 8:43am UTC](https://help.galaxyproject.org/t/troubleshooting-for-an-error-in-galaxy-training-materials-reference-based-rna-seq-data-analysis/16443/2 "2025-10-29T08:43:31Z")

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Hi @musfira ,

the tool used for the mapping step has recently been updated and I think this is not yet reflected in the tutorial. The long story is that the tool now accepts only _collection_ input, not two separate datasets anymore, but for the purpose of following the tutorial you can just switch back to an older version of the tool as explained here: [Bowtie2 on galaxy europe platform does not work - #5 by wm75](https://help.galaxyproject.org/t/bowtie2-on-galaxy-europe-platform-does-not-work/16341/5) . You should then be able to proceed just as described.