Use the following steps to resolve the “At least one signature is invalid.” message.

Contents


Complete the initial configuration

1. For Adobe Acrobat XI or Adobe Reader XI or Adobe Acrobat Reader DC

  • Preferences

1. Launch Acrobat or Adobe Reader.

2. From the [Edit] menu, click [Preferences].

3. The [Preferences] dialog box is displayed.

4. a) From the panel on the left side, click [Signatures].

5. b) In [Verification], click the [More] button.

6. The [Signature Verification Preferences] dialog box is displayed.

7. c) Select the checkboxes for both [Validating Signatures] and [Validating Certified Documents] in the Windows Integration section.

8. Click [OK] to close the [Preferences] dialog box.

  • Checking signatures

Open the PDF file for which to verify in Acrobat or Adobe Reader, and perform the following steps.

a) Click the [Signature Panel] in the navigation bar.

b) Click [Validate All].


2. For Adobe Acrobat X or Adobe Reader X

  • Preferences

  1. Launch Acrobat or Adobe Reader.

  2. From the [Edit] menu, click [Preferences].

  3. The [Preferences] dialog box is displayed.

  4. a) From the panel on the left side, click [Security].

  5. b) Click the [Advanced Preferences] button.

  6. 6. The [Digital Signatures Advanced Preferences] dialog box is displayed.

  7. c) Select the [Windows Integration] tab.

  8. d) Select the checkboxes for both [Validating Signatures] and [Validating Certified Documents].

  9. Click [OK] to close the [Preferences] dialog box.

 

  • Checking signatures

Open the PDF file for which to verify in Acrobat or Adobe Reader, and perform the following steps.

 

a) Click the [Signature Panel] in the navigation bar.

b) Click [Validate All].


If the problem persists

If the steps above do not solve the problem, try the following method.

  1. Launch Acrobat or Adobe Reader.

  2. From the [Edit] menu, click [Preferences].

  3. The [Preferences] dialog box is displayed.

  4. a) From the panel on the left side, click [Trust Manager].

  5. b) Select the [Load trusted certificates from an Adobe AATL server] checkbox.

  6. c) Click [Update Now].

  7. The [Security settings have been successfully updated.] dialog box is displayed.

  8. Click [OK] to close the [Security settings have been successfully updated.] dialog box.

  9. Click [OK] to close the [Preferences] dialog box.

*Reference (Adobe website)

Acrobat Help / Validating digital signatures - Setting up digital signature validation

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