Make Sure That Your Head Markup Is Valid
Do you have custom markup in your <head> markup? To improve security, in Summer ‘19 all existing code must be
compliant for the <head> to function, and all new code
must be compliant to be saved. This enhancement builds on the changes introduced in Winter ‘18
that applied extra restriction to <head>.
Where: This change applies to Lightning communities, accessed through Lightning Experience and Salesforce Classic. Communities are available in Enterprise, Performance, Unlimited, and Developer editions.
How: Wondering if your code is OK? Check the Head Markup section in the Advanced Settings tab of Community Builder. If you have invalid code, you see an alert to fix it. When you are adding code, watch for the indicators in the code window. But even if you miss that, we let you know if and where you have an issue when you try to save.