Forms upload for guests are not working after changing the mail domain in Instance Settings

Issue

• This article describes a known issue with guests uploads in Forms after changes to a Liferay DXP instance's mail domain.
• In this situation, you will see symptoms such as an error message in the UI indicating

  "An unexpected error occurred while uploading your file."

Environment

• Liferay DXP 7.3
• Liferay DXP 7.4 Update 75 and under

Resolution

• In Liferay DXP 7.3, please open a support ticket on Liferay Help Center with a request for a hotfix which includes the fix for LPS-182948.
• In Liferay DXP 7.4, please update to Update 76 or above. Or in the alternative, please create a ticket on Help Center requesting a hotfix which includes the fix for LPS-182948.

Additional Information

• After mail domain change, guest user cannot upload images (LPS-182948)