Cloudflare Wrangler throws ByteString conversion error when setting secret with Unicode character

What this error means

[ERROR] Cannot convert argument to a ByteString because the character at index 7 has a value of 8230 which is greater than 255 is a Cloudflare failure pattern reported for developers trying to resolve wrangler secret put failure when input contains non-ascii characters (unicode > 255). Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub issue cloudflare/workers-sdk#13997 — npx wrangler secret put fails with ByteString conversion error when secret value contains Unicode character (ellipsis U+2026, value 8230). Users must avoid special chars in secrets, impacting production deployments on Cloudflare Workers Enterprise plan.

Common causes

• GitHub issue cloudflare/workers-sdk#13997 — npx wrangler secret put fails with ByteString conversion error when secret value contains Unicode character (ellipsis U+2026, value 8230). Users must avoid special chars in secrets, impacting production deployments on Cloudflare Workers Enterprise plan.

Quick fixes

1. Confirm the exact error signature matches [ERROR] Cannot convert argument to a ByteString because the character at index 7 has a value of 8230 which is greater than 255.
2. Check the Cloudflare account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/cloudflare/workers-sdk/issues/13997

Evidence note: GitHub issue cloudflare/workers-sdk#13997 — npx wrangler secret put fails with ByteString conversion error when secret value contains Unicode character (ellipsis U+2026, value 8230). Users must avoid special chars in secrets, impacting production deployments on Cloudflare Workers Enterprise plan.

Related errors

• Cloudflare

FAQ

What should I check first?

Start with the exact [ERROR] Cannot convert argument to a ByteString because the character at index 7 has a value of 8230 which is greater than 255 text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Cloudflare workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without [ERROR] Cannot convert argument to a ByteString because the character at index 7 has a value of 8230 which is greater than 255.