Embodiments are directed to maintaining coherence between web application versions, to maintaining proper versions between web application clients and servers and to determining whether to apply a web application update. In one scenario, a computer system receives a data request from a web application client for certain specified data. The data is indexed according to a web application schema, and the data request includes a web application client version identifier. The computer system determines that the requested data is not accessible using the web application schema, updates the web application schema to a current version of the web application schema and processes the received data request using the updated web application schema.