"The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters." error when attempting to run a workflow.

August 8, 2025 | KB: 1014530

https://support.laserfiche.com/kb/1014530/the-input-is-not-a-valid-base-64-string-as-it-contains-a-non-base-64-character-more-than-two-padding-characters-or-an-illegal-character-among-the-padding-characters-error-when-attempting-to-run-a-workflow-

Workflow 11

When attempting to view or run a workflow using Workflow Designer, you may receive the following error message:

The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.

You are attempting to view or run a workflow using a version of Workflow Designer that is newer than the Workflow Server.
You are attempting to view a workflow that was published in version 11.0.2306.898 using an older version of Workflow Designer. Workflow 11.0.2306.898 upgraded encryption algorithms for added security. Older clients may not able to decrypt workflows.

Ensure Workflow Designer and Workflow Server are on the same version.