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Stirling PDF: visible signing fails on non-ASCII names

Separate visible-signature font errors from token access and cryptographic signature validation.

Source date: 5 November 2026Editorial team: KAN KAI WORKSEditorially updated:

Quick answer

A visible certificate signature failing with Times-Bold or WinAnsiEncoding may involve rendering the signer's name rather than an invalid signing key. Compare visible and invisible signing on a harmless test document using the same certificate, and record the exact Unicode error. Do not alter legally significant names to bypass it; a visible stamp alone also does not establish a technically valid signature.

Source basis: Q1 · Q2

Applies to
The archived report concerns Stirling PDF Desktop 2.14.x on Windows and non-ASCII signer names. The available evidence does not verify a generally fixed release.
How to verify the result
Required characters appear correctly in the exported document, technical signature validation produces the expected result, and the file satisfies the intended signing workflow.
Your first check

Does only the visible signature appearance fail?

Use a harmless test PDF to compare visible and invisible signing with the same intended certificate. Record whether failure occurs before a PIN prompt.

Stirling PDF stops visible signing with an error mentioning Times-Bold, WinAnsiEncoding and a Unicode character such as U+0159. An archived original report for desktop 2.14.x describes this with a non-ASCII signer name before the PIN prompt. Invisible signing worked in that report's comparison. This is a bounded incident, not a confirmed defect in every current release. Q1

Separate appearance from signing

A visible signature field contains readable text. Processing that text is a distinct concern from using the certificate itself. The current manufacturer guide offers visible and invisible appearances plus a separate signature-validation operation. Q2 A font encoding error therefore does not by itself establish a faulty USB token or incorrect password.

Diagnose with a harmless document

  1. Preserve the original. Use a newly created, non-sensitive test file. Avoid repeatedly modifying an already signed contract to investigate the problem. Record desktop or server version and the certificate source.
  2. Capture the first error. Keep the font name, encoding and affected character code. Redact personal names when necessary. Whether failure occurs before or after token access narrows the stage more usefully than a general statement that signing fails.
  3. Compare appearance options. Within an authorised test, use the same certificate source for visible and invisible signing. Keep token driver and certificate unchanged. If only the invisible option works, focus investigation on generation of the visible appearance.
  4. Identify the text source. Determine whether the character comes from the certificate name, a reason field or a template. Do not change the certificate identity to conceal an appearance bug. For a custom integration, include font character coverage in the minimal reproduction.
  5. Validate the resulting file. Check both signature status and visible content after export. Creating a PDF successfully does not itself establish certificate trust or satisfaction of every requirement in the intended signing workflow.

Evaluate a temporary operating option

An invisible appearance is only an appropriate interim option if the specific workflow permits it and the resulting signature passes the required technical checks. It is not a general statement about legal signature classification. A maintainer report should use a minimal sample reproducing the relevant character type without confidential contents.

For handoff, prepare version, platform, certificate source, exact error and both comparison results. Do not include private keys, token PINs or certificate containers holding secret material in the initial description. Preserve the test procedure so that a later vendor correction can be assessed using the same evidence.

Frequently asked questions

Should I remove accents from the signer name?

Not from the certificate identity. Identify the failing appearance layer and its supported character handling.

Does a visible signature prove validity?

The visible field does not replace technical signature and trust validation of the saved document.

Describe your case

Support with this issue

We can investigate signature appearance, character handling and the documented signing sequence.

Describe your case →Related service: Data & improvements

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