For Picasa questions, please ask for help at the Google Photos forum: https://support.google.com/photos/community
This Photos Resources site is provided by Google Photos Product Experts and former Picasa Top Contributors to help users with Google Photos, and Picasa.
On February 12, 2016, Google announced retirement plans of Picasa3 and Picasa Web Albums in their "Moving on from Picasa" blog: "As of March 15, 2016, we will no longer be supporting the Picasa desktop application." The Picasa installation file was removed from Google's help center shortly thereafter.
The following information is from Google's announcement, Moving on from Picasa:
"We’ve decided to retire Picasa in order to focus on a single photo service in Google Photos – a new, smarter photo app that works seamlessly across mobile and the web. For those who have already downloaded it, it will continue to work as it does today. But we will not be developing it further, and there will be no future updates. Some functions of the Picasa API were retired. We apologize for any inconvenience this transition causes, but we want to assure you that we’re doing this with the aim of providing the best photos experience possible. Google Photos is a new and smarter product that offers a better platform for us to build amazing experiences and features for you in the future."
Comment:
"we’re doing this with the aim of providing the best photos experience possible"
That of course is not correct. They could have replaced Picasaweb by Google Photos, while keeping Picasa alive and even improve it. Picasa and Picasaweb worked together for a great experience, but Google preferred to ignore the legacy Picasa users. Even worse: Google Photos may have more fancy AI features, it is missing some really basic tools like sorting by file name in albums.
Picasa3, the desktop program, see: Picasa retirement
Picasa Web Albums and/or Blogger users, see: Picasaweb retirement
See "Picasa is Dead. Long Live Picasa!" at the Geeks On Tour website
The Photos Resources site is provided by former Picasa Top Contributors to help users with Google Photos, Picasa3 and Album Archives (the retired Picasa Web Albums website).
The following were our Top Contributor volunteers at the Picasa forum over the years, and many of them helped to write the information found at this user-to-user help website: Alexander, Mike, Rhubarb, Pixelshooter, SanFranMan, Byteguy, earlboss, Jim2, the_roggy, geo.osm, Janvb, Onion Zwiebel, Phil KL, Don Lind, and Tom O'Haver. The actual maintenance is done by Janvb and Onion Zwiebel.
Picasa Top Contributors are users with a passion for the Picasa product. They volunteered their time to help answer other user's questions. In the beginning, these helpful people had no official title. In 2005, Google began a program to recognize knowledgeable and active forum posters. Around 2008, these forum posters were known as Picasa Super Users. The title later changed to Picasa Top Contributor. Before the evolution of the new "Product Expert" title, Picasa and Picasa Web Albums were retired by Google. It was very disappointing news for Picasa users all over the world. Some of the Picasa contributors joined the Google Photos forum and continued helping Picasa users there.
Those interested in Google Photos can apply to become a "Product Expert": Product Expert website