I am having a document Library in SPO. When I click on the list alerts I am getting an error:
Nothing is said in this message.
I am having "Designer" permissions with the right "Manage alerts" enabled, can any one help on how to fix this issue?
It’s the default behavior that user cannot create alert when we set read access on their own items.
As a workaround, you can create a custom workflow to use “send email” action and start workflow automatically when the item changed in SharePoint Designer.
Here is a similar post for your reference.
I would just add to Hellofiona's answer by explaining something which she alludes to. If you check in the List Settings>Advanced Settings.
Hellofiona suggests that you need to check that 'Read access' is set to Read all items and not 'Read items that were created by the user'.