ANSI escape codes shown instead of colored output in Nextflow 24.10.0 when running nf-core/rnafusion

[tkcaccia]

Describe the bug While running the nf-core/rnafusion pipeline with Nextflow v24.10.0, I suddenly started seeing raw ANSI escape sequences (^[[1m, ^[[33m, etc.) in the terminal or log output instead of proper colored formatting.

This behavior was not present before using the same version of Nextflow — output was correctly colorized. I have not changed Nextflow versions, and the issue began unexpectedly.

I do not want monochrome logs — I want terminal colors to display properly, just like they did before.

To Reproduce Command:

bash Copy Edit nextflow run nf-core/rnafusion -r 3.0.2 Behavior:

Terminal shows raw ANSI codes

.nextflow.log also includes unrendered escape codes

Expected behavior

Terminal output should be properly colorized (as it was previously under the same version)

Logs may contain ANSI codes, but terminal rendering should be readable

Screenshots or output

text Copy Edit ^[[1m^[[38;5;232m^[[48;5;43m N E X T F L O W ^[[0;2m ~ version 24.10.0^[[m Environment:

Nextflow version: 24.10.0

Pipeline: nf-core/rnafusion v3.0.2

OS: Linux (HPC SLURM environment)

Shell: Bash via SSH

$TERM: xterm-256color

No output redirection used

Additional context

The same exact setup showed colors correctly before.

The issue appeared without any change in Nextflow version or configuration.

I have not set --ansi-log false or params.monochromeLogs.

I’d like to preserve colored output in the terminal, without seeing raw ANSI sequences.

Please let me know if this might relate to internal logging or environment detection, or how I can revert to the previous behavior.

Would you like me to help test this with different $TERM or Nextflow flags to isolate the cause?