When you use the same context in more than one configuration page such as Technical Attributes, Help texts, Label Override and so on, a single shared tag is created for that context. The tag stores a reference to every screen that uses the context in the SVMXC__Tag_Context__c field. When the combined list of references is longer than 255 characters, save fails and an error appears in the configuration page.

Change the context on the page where save fails so that it differs from the context on the other screens. A unique context creates a new tag and keeps the SVMXC__Tag_Context__c field within the 255-character limit