I have encountered an issue while using Omeka. The error message appears on the screen after I click the “Add an Item” button, but it seems not to affect the uploading of documents and metadata. Below is the error message it shows.
The link in the image you posted leads to a manual page that gives you instructions on how to make an actual error message appear here. You’ll have to follow those instructions and share the error message you get for us to be able to help you.