What does "Error: invalid_grant" mean?

You can get this error when your browser experiences caching conflicts.

To fix this, here are recommended steps:

• Use Chrome Incognito window. File > New Incognito Window
• Sign out of other Google accounts you might be signed into
• Clear cache and cookies
• Use Chrome and set up one Chrome profile per email address. Please refer to the Add a person or profile section in the following article: https://support.google.com/chrome/answer/2364824?co=GENIE.Platform%3DDesktop&hl=en
• Keep your browser up to date. Direct link: chrome://settings/help

If the above steps fail to resolve the issue, try removing then re-granting app permissions for Form Workflow Plus. Here are the steps:

1. Visit the app permissions page: https://myaccount.google.com/permissions
2. Look for and click on Form Workflow Plus entries.​
3. Click on Remove Access​
4. Log out of G Suite as well as the Form Workflow Plus web app
5. Log back in to G Suite and Form Workflow Plus web app making sure you grant app permissions when asked