error occurring when resetting io pointer in '%s': %w

Error message

error occurring when resetting io pointer in '%s': %w

What it means

Returned when f.Seek(0, 0) fails after a workflow file was successfully read — act rewinds the file descriptor so later consumers can re-read the raw bytes. Seek on a regular file virtually never fails; this error indicates the reader is not a seekable *os.File (unusual injection) or the fd is closed/broken.

Source

Thrown at pkg/model/planner.go:138

		if ext == ".yml" || ext == ".yaml" {
			f, err := os.Open(filepath.Join(wf.dirPath, wf.workflowDirEntry.Name()))
			if err != nil {
				return nil, err
			}

			log.Debugf("Reading workflow '%s'", f.Name())
			workflow, err := ReadWorkflow(f, strict)
			if err != nil {
				_ = f.Close()
				if err == io.EOF {
					return nil, fmt.Errorf("unable to read workflow '%s': file is empty: %w", wf.workflowDirEntry.Name(), err)
				}
				return nil, fmt.Errorf("workflow is not valid. '%s': %w", wf.workflowDirEntry.Name(), err)
			}
			_, err = f.Seek(0, 0)
			if err != nil {
				_ = f.Close()
				return nil, fmt.Errorf("error occurring when resetting io pointer in '%s': %w", wf.workflowDirEntry.Name(), err)
			}

			workflow.File = wf.workflowDirEntry.Name()
			if workflow.Name == "" {
				workflow.Name = wf.workflowDirEntry.Name()
			}

			err = validateJobName(workflow)
			if err != nil {
				_ = f.Close()
				return nil, err
			}

			wp.workflows = append(wp.workflows, workflow)
			_ = f.Close()
		}
	}

View on GitHub (pinned to 4f41128141)

Solutions

Ensure .github/workflows contains only regular files (no FIFOs/symlinks to pipes).
Re-run — if it persists on one machine, check the filesystem health (NFS/FUSE mounts) hosting the repo.
If embedding act, make sure nothing closes the *os.File between planning phases.

Defensive patterns

Strategy: try-catch

Validate before calling

fi, err := entry.Info()
if err != nil || !fi.Mode().IsRegular() {
    return fmt.Errorf("%s is not a regular file", entry.Name()) // skip FIFOs/special files
}

Try / catch

if err != nil && strings.Contains(err.Error(), "resetting io pointer") {
    // check mount/filesystem health; retry after remounting or moving the repo to local disk
}

Prevention

Keep the repository on a local, fully POSIX filesystem.
Do not place special files in .github/workflows.
If embedding act, never pass non-seekable readers into the planner.

When it happens

Trigger: Passing a non-seekable or already-closed file descriptor into the workflow directory scan path; file deleted or fd invalidated between Open and Seek; exotic filesystems that reject seek on an open handle.

Common situations: Almost never seen by end users; mostly reachable in embedded/test contexts where the planner is fed pipes or mock readers, or on flaky NFS/FUSE mounts during CI.

Related errors

AI-assisted analysis of nektos/act@4f41128141 (2026-08-15). Data as JSON: /api/errors/12ba9da3664df50b. Report an issue: GitHub.