On a day that was supposed to mark a new era of online testing in Tennessee, a major technology failure led State Department of Education officials to scrap their new online exam and revert to paper-and-pencil tests.

Within minutes after some schools statewide began administering the TNReady test developed by North Carolina-based Measurement Inc., the company’s online platform experienced a severe network outage, prompting state officials to order districts to stop the testing immediately if they were experiencing technical difficulties.

By the end of the day, the issues not resolved, Education Commissioner Candice McQueen emailed district directors to stop the process altogether because, she said, “we are not confident in the system’s ability to perform consistently.”

The admission and change of plans are a major blow to McQueen and her Education Department, which have worked with Measurement Inc. since October 2014 to develop a new assessment that moves Tennessee schools to online testing and also is aligned with Tennessee’s current Common Core standards. Even before then, the state had prepared for years for the switch to online testing.

“Like you, we are incredibly disappointed that the MIST platform was not accessible to schools across the state as the Part I testing window opened,” McQueen wrote directors. “We understand that the shift to paper and pencil testing has many scheduling implications for your schools, teachers, and students. We thank you for your patience and cooperation as we transition to a test medium that we are confident will allow all students to show what they know.”

Just last week, state education leaders briefed reporters about contingency plans if technical glitches or system failures occurred. The plan was to give individual districts discretion in ordering backup paper-based tests, plus flexibility in taking the test outside the testing window, scheduled for Feb. 8 through March 4.

State education officials never hinted that a technical failure of this magnitude was a possibility. In fact, they expressed optimism in the wake of months of capacity tests, significant investments in server capacity, and on-the-ground visits to local districts that tested the program.

But after Monday’s fiasco and concerned about more disruptions, state officials didn’t even attempt to salvage TNReady’s online exam for the second part of the testing window, scheduled for April 18 through May 13.

“Despite the many improvements the department has helped to make to the system in recent months and based on the events of this morning, we are not confident in the system’s ability to perform consistently,” McQueen wrote. “In the best interest of our students and to protect instructional time, we cannot continue with Measurement Incorporated’s online testing platform in its current state.”

Even with years and months of preparation, teachers had been increasingly skeptical of whether the state and their districts were ready for TNReady.

“Any teacher would have told you there was going to be a problem,” said Mary Holden, a Nashville parent and English III teacher at Centennial High School in Franklin. “Hello, wake up! It is not rocket science to figure out there are going to be issues with online testing the first time you do it.”

Molly Handler, a fourth-grade teacher at Glenn Enhanced Option Elementary School in Nashville, said glitches on practice tests throughout the year prepared her for the worst.

“Honestly, it’s not a huge source of stress because we knew (there would be problems), and there was nothing we could do about it,” she said. “So we really just focused on teaching.”

In Memphis, the delay left teachers scrambling to restructure lesson plans for the next few weeks, said Ryan Winn, a seventh-grade math teacher at KIPP Memphis Academy Middle School.

“There’s a lot of uncertainty moving forward,” he said.

A full week before the testing window began, officials of RePublic Schools — a Nashville-based charter organization known for its expansive technical resources and also openly supportive of the state’s transition to TNReady — outlined concerns in a letter to McQueen. They said half of their students were unable to log on to the testing platform only days before the test, making them wary of the chances that students statewide would be able to log on.

“Here’s what we believe should happen: Schools should be confident that they can administer the tests on any day or days within the testing window that work best for their students and teachers,” the letter said. “Students should be confident that when they sit down to take an exam that the only thing they need to think about is how best to demonstrate what they know.”

Initially, Tennessee was supposed to use funds under the state’s federal Race to the Top award to roll out the PARCC test, which is also an online test aligned with Common Core, during the 2014-15 school year. However, wary of federal intrusion in state testing policies, the legislature instead voted to stick with the TCAP test for 2015-2016 and open up bids for a new testing vendor. That led the state to award a $108 million contract to Measurement Inc., which offered the lowest bid.

Memphis reporter Laura Faith Kebede contributed to this report.