kestra-io/kestra · error · IllegalArgumentException

Cannot process the URI %s: scheme not supported.

Error message

Cannot process the URI %s: scheme not supported.

What it means

Inside AbstractFileFunction.execute(), after checking the supported schemes (kestra:///, file://, namespace://), if the string still matches the generic URI pattern (scheme:something) an IllegalArgumentException is thrown with 'Cannot process the URI %s: scheme not supported.' The surrounding catch wraps it into a PebbleException carrying e.getMessage().

Source

Thrown at core/src/main/java/io/kestra/core/runners/pebble/functions/AbstractFileFunction.java:91

            Map<String, String> flow = (Map<String, String>) context.getVariable("flow");
            String tenantId = flow.get(TENANT_ID);

            if (path instanceof URI uri) {
                fileUri = uri;
                namespace = checkAllowedFileAndReturnNamespace(context, fileUri);
            } else if (path instanceof String str) {
                if (str.startsWith(KESTRA_SCHEME)) {
                    fileUri = URI.create(str);
                    namespace = checkAllowedFileAndReturnNamespace(context, fileUri);
                } else if (str.startsWith(LocalPath.FILE_PROTOCOL)) {
                    fileUri = URI.create(str);
                    namespace = checkEnabledLocalFileAndReturnNamespace(args, flow);
                } else if (str.startsWith(Namespace.NAMESPACE_FILE_SCHEME)) {
                    fileUri = URI.create(str);
                    namespace = checkedAllowedNamespaceAndReturnNamespace(args, fileUri, tenantId, flow);
                } else if (URI_PATTERN.matcher(str).matches()) {
                    // it is an unsupported URI
                    throw new IllegalArgumentException(SCHEME_NOT_SUPPORTED_ERROR.formatted(str));
                } else {
                    fileUri = URI.create(Namespace.NAMESPACE_FILE_SCHEME + ":///" + str);
                    namespace = (String) Optional.ofNullable(args.get(NAMESPACE)).orElse(flow.get(NAMESPACE));
                    namespaceService.get().checkAllowedNamespace(tenantId, namespace, tenantId, flow.get(NAMESPACE));
                }
            } else {
                throw new PebbleException(null, "Unable to read the file " + path, lineNumber, self.getName());
            }
            return fileFunction(context, fileUri, namespace, tenantId, args);
        } catch (IOException | IllegalArgumentException e) { // IllegalArgumentException may be thrown for path traversal, catch it to have proper error handling
            throw new PebbleException(e, e.getMessage(), lineNumber, self.getName());
        }
    }

    @Override
    public List<String> getArgumentNames() {
        return List.of(PATH, NAMESPACE);
    }

View on GitHub (pinned to 823fada927)

Solutions

1. Use an HTTP task (e.g. io.kestra.plugin.core.http.Request) to fetch remote URLs, then read the downloaded internal-storage URI.
2. Convert remote content into a kestra:/// internal storage URI before passing to read().
3. For namespace files use the namespace:// scheme; for local worker files use file:// (if enabled).

Example fix

// before
{{ read('https://example.com/data.json') }}
// after
id: fetch
namespace: company.team
tasks:
  - id: http
    type: io.kestra.plugin.core.http.Request
    uri: https://example.com/data.json
  - id: use
    type: io.kestra.plugin.core.log.Log
    message: "{{ read(outputs.http.body) }}"

// Pebble: only kestra:///, file://, namespace:// are allowed
{% set u = outputs.x.uri %}{{ (u starts with 'kestra://' or u starts with 'namespace://' or u starts with 'file://') ? read(u) : '' }}

When it happens

Trigger: Passing an http/https/ftp/s3/custom-scheme URI to read(): {{ read('https://example.com/data.json') }}. Any scheme other than kestra, file, or namespace triggers it.

Common situations: Trying to read a remote URL directly with read() (which is internal-storage only); pasting a public URL expecting an HTTP fetch; plugin confusion about which function fetches remote content.

Related errors

• Unable to read the file '{path}' as it is not an execution f
• getErrorMessage() [abstract: subclass-defined ERROR_MESSAGE]
• Unable to read the file {path}
• IOException|IllegalArgumentException: e.getMessage()
• You cannot set a namespace both as the function argument and

AI-assisted analysis of kestra-io/kestra@823fada927 (2026-08-14). Data as JSON: /api/errors/aa8c5ce15d5cec43. Report an issue: GitHub.