java.lang.IllegalArgumentException: Could not build the path

Hi,

I am new to FireCloud and trying to run my first workflow.

Specifically, I am trying to launch the haplotypecaller-gvcf-gatk4 workflow using a BAM file (and index) I have already generated.

I imported the haplotypecaller-gvcf-gatk4 method/configuration to my workspace. I uploaded the relevant files including my BAM and index to the provided google cloud bucket and imported metadata. I have set the relevant workspace attributes. I am using the Root Entity Type participant to launch the workflow.

However, when I run the workflow I get this from the generated log file:
ERROR - PipelinesApiAsyncBackendJobExecutionActor [UUID(9f6d0589)HaplotypeCallerGvcf_GATK4.HaplotypeCaller:1:1]: Error attempting to Execute
cromwell.core.path.PathParsingException: java.lang.IllegalArgumentException: Could not build the path " workspace.ref_fasta_index". It may refer to a filesystem not supported by this instance of Cromwell. Supported filesystems are: Google Cloud Storage. Failures: Google Cloud Storage: Path " workspace.ref_fasta_index" does not have a gcs scheme (IllegalArgumentException) Please refer to the documentation for more information on how to configure filesystems: cromwell.readthedocs.io/en/develop/backends/HPC/#filesystems

I am not sure why I am getting this error message because ref_fasta_index workspace attribute is to a file on the generated google cloud storage bucket and seems to have loaded fine as shown by the attached image. I have also set four other workspace attributes in the exact same way and am not getting any errors for those.

Do you know what's causing this issue and how it can be resolved?

Many thanks in advanance