Fix Acrobat Pro 2017 Digital Signature Validation Errors
Question details
The user wants to confirm if Acrobat Pro 2017 supports digital signatures and needs to know how to resolve warnings where recipients see the signature as invalid or untrusted.
- Product
- Adobe Acrobat Pro 2017
- Device & OS
- not provided
- Scenario
- Applying digital signatures to PDF documents and sharing them with recipients for verification.
- Observed behavior
- Recipients receive warnings indicating that the document's digital signature is invalid, untrusted, or incomplete, despite being signed in a supported Pro version.
Ensure you have an active internet connection so the software can properly communicate with certificate authorities to validate the signature chain.
Update Acrobat Pro 2017 to the Latest Version
Running outdated software can cause compatibility issues with modern digital signature validations, leading to false warning messages.
Acrobat Pro 2017 (a perpetual-license product) and Acrobat Pro DC (a subscription product) both fully support digital document signing.
However, digital signature security standards evolve constantly. Keeping your software updated ensures it can properly read newer certificate formats.
Launch your Adobe Acrobat Pro 2017 application on your computer.
Navigate to the 'Help' menu in the top toolbar and click on 'Check for Updates'.
If an update is found, follow the on-screen prompts to download and install it, then restart the application.
Validate and Trust the Signer's Certificate
If a recipient sees an 'invalid signature' warning, their local PDF reader may simply not trust the certificate authority that issued the signature.
Verify Document Integrity and Certificate Expiration
Signatures become invalid if the document was altered after signing or if the signing certificate has expired.
Add Valid Digital Signatures using WPS PDF
If you continue to experience compatibility or validation errors with older PDF software, try WPS Office. It provides an intuitive, modern PDF tool to securely sign documents, validate certificates, and share files seamlessly without triggering invalid warnings.
- 1. Open your PDF: Launch WPS Office and open the PDF document you need to sign.
- 2. Navigate to the signature tool: Go to the 'Protect' or 'Fill & Sign' tab on the top ribbon and select the 'Sign' option.
- 3. Apply your signature: Create a new digital signature, import your existing certificate, and click on the document to place it securely.
- 4. Save and share: Save the securely signed PDF. The signature will be recognized as valid by standard PDF readers.
Frequently Asked Questions
Does Acrobat Pro 2017 support digital signatures like Acrobat Pro DC?
Yes, both Acrobat Pro 2017 (perpetual license) and Acrobat Pro DC (subscription) fully support viewing, creating, and validating digital signatures. Ensure your version is fully updated to avoid compatibility issues.
Why does my valid signature show as 'Unknown' to recipients?
An 'Unknown' or 'Invalid' warning usually means the recipient's PDF viewer has not established trust with the certificate authority that issued your signature. The recipient may need to manually add your certificate to their trusted identities list.
How do I know if a signed PDF document has been altered?
When you open a signed PDF, the signature panel will display a warning message stating 'Document has been modified or corrupted since it was signed' if any unauthorized changes were made after the signature was applied.
