Mohamed Rafiq, a developer who writes a Google+ news blog, agreed that Google should have released a sandbox version of Wednesday's update. But, he said, he couldn't fault Google because the company has made clear that it is continuing to make changes to the social networking platform, which launched in beta in September 2011.

"When there is an official API, they don't do this," said Rafiq, who has shied away from building extensions for Google+ but has worked with the company's app engine. Mansour also described positive experiences working with Google on Chrome.

But Google+ user Kosso K pointed to an irony in Google's position. The company avoids issuing an API that could change frequently so as not to anger developers, "and yet they do things like this, with no warning at all."

Asked for comment, Google PR provided a statement attributed to David Glazer, the engineering director for Google+: "We appreciate and value developers contributing to our platforms and services, and continue to develop and support our official API. We can't support applications built on undocumented, unofficial APIs, including those based on reverse-engineering."

The IDG News Service