Import List Failing to preview

Last update: August 18, 2026

Description description

You are attempting to import a list to Marketo. After you upload the list and click next, the system hangs on the loading screen.

Resolution resolution

This is caused by unsupported characters in the file’s content. In order to upload to Marketo the characters need to be UTF-8 supported, if not the preview will fail to load.

Here’s a quick way you can check if this is the cause:

create a new blank .csv file
copy the headers and one line of the file without any unusual-looking characters
try to import, it should work
then try to import with a line that contains the unusual characters
if this fails, remove the characters in question and check again

recommendation-more-help

experience-cloud-kcs-help-kbarticles