Also in the quarter, Unify Square signed contracts with nearly 20 new logo clients, including consulting contracts and Power Suite software subscriptions focused on migrating to or managing Zoom and Microsoft Teams, UCaaS environments.
Revenue growth continued during the third quarter in C&I with Cloud revenue specifically growing 26% year-over-year.
We recently signed a contract with New Zealand's Waka Kotahi NZ Transport agency to extend our engagement to manage IT infrastructure on the ClearPath Forward platform that supports systems processing approximately 25 million driver's license and 60 million motor vehicle transactions per year.
Our total company TCV was up 13% year-over-year in the third quarter, and total ACV was up 30% year-over-year.
Total company pipeline was also up 5% sequentially, supported by growth in our proactive experienced DWS solutions and Cloud solutions pipelines, which increased sequentially, both on a dollar basis and as a percent of total pipeline.
Our last 12-month voluntary attrition was 15.3%, which is significantly below the pre-pandemic level of 17% for the third quarter of 2019.
The demand for open roles filled internally as a percent of total, increased six points for the year-to-date versus 2020 to 36%, reflecting the effectiveness of our internal development, mobility programs and upskilling and referrals represent over 20% of total hiring on a year-to-year basis.
Overall, our year-to-date performance is in line with our internal expectations, and we are reaffirming all full year 2021 guidance metrics as a result.
Our ongoing enhancements to our Cloud capabilities and efforts to increase awareness with industry analysts and clients continue to yield results with C&I revenue growth of 1.7% year-over-year to $118.9 million in the third quarter.
This was supported by Cloud revenue growth within the segment of 26% year-over-year.
ECS revenue grew 1.8% year-over-year.
ECS services revenue grew 1% year-over-year.
As we've previously noted, we had expected the third quarter to be the lightest of the year in terms of license revenue, which we still expect to be split approximately 55% and 45% between the first and second half of the year.
As a reminder, the prior year first half/second half split was 40% -- 60%, with 40% of the full year segment revenue coming in the fourth quarter.
We also saw some impacts related to supply chain shortages, and both of these items impacted revenue, which was down 4.7% year-over-year to $141.3 million.
As a result of all of this, the total company revenue was down 1.5% year-over-year in the third quarter to $488 million.
As I noted, though, this does not change our expectations for revenue for the full year as this quarterly cadence was anticipated and was embedded in our guidance, as was our expectation for year-over-year decline in the fourth quarter revenue due to the timing issues I mentioned, which is why we're reaffirming that guidance at 0% to 2% year-over-year revenue growth.
As a result, total company backlog was $3 billion as of the end of the third quarter relative to $3.3 billion as of the end of the prior quarter.
Of the $3 billion in backlog, we expect approximately $380 million will convert into revenue in the fourth quarter.
C&I gross profit increased 116.3% year-over-year to $9.3 million, and gross margin improved 410 basis points to 7.8%, driven by the improvements to margin in both Cloud and traditional infrastructure work.
ECS gross profit increased 28.8% year-over-year to $97 million, and gross margin improved 1,360 basis points to 65%, helped by the higher revenue I mentioned earlier.
DWS gross profit was $16.8 million relative to $21.6 million in the prior year period, largely driven by the flow-through impact of lower revenue.
DWS gross margin was 11.9% relative to 14.6% in the prior year period.
As with revenue, our year-to-date non-GAAP operating profit margin results are roughly in line with internal expectations, and accordingly, we're reaffirming our full year 2021 guidance for this metric at 9% to 10%.
As a result, total company non-GAAP operating profit margin was 5.7% relative to 8.6% in the prior year period.
The annualized savings associated with this program are at the high end of the targeted range we provided, which was $130 million to $160 million.
Our net loss from continuing operations was $18.7 million or $0.28 per diluted share versus $13.3 million or $0.21 per diluted share in the prior year period.
Non-GAAP net income was $6.9 million versus $36.8 million in the prior year period, and non-GAAP diluted earnings per share was $0.10 versus $0.51 in the prior year period.
As with revenue and non-GAAP operating profit margin, our year-to-date adjusted EBITDA results are generally in line with our expectations, and so we are reaffirming full year 2021 guidance for this metric at 17.25% to 18.25%.
Adjusted EBITDA in the quarter was $74.6 million relative to $82.3 million in the prior year period, and adjusted EBITDA margin in the quarter was 15.3% versus 16.6% in the prior year period based on similar drivers as non-GAAP operating profit and margin.
Our capital expenditures declined year-over-year again in the third quarter, down 18.4% to $26.1 million.
We now expect capex to be between 100 and $110 million for the full year 2021, which is lower than our previous expectations.
Free cash flow and adjusted free cash flow also continued to improve, with free cash flow up 14.9% year-over-year to $39.4 million and adjusted free cash flow up 36.3% to $69.9 million.
In continuing our efforts to further derisk our balance sheet, we completed a transfer of additional gross pension liabilities in October through a $235 million annuity contract.
We expect a onetime noncash pre-tax settlement charge in the fourth quarter associated with this liability transfer of approximately $130 million or $1.94 per share.
Mike will be taking on the role of President and Chief Operating Officer, effective upon the hiring of a new CFO.
At that point, he will transition to President and Chief Operating Officer.

Summary:
Overall, our year-to-date performance is in line with our internal expectations, and we are reaffirming all full year 2021 guidance metrics as a result.
As a result of all of this, the total company revenue was down 1.5% year-over-year in the third quarter to $488 million.
As a result, total company backlog was $3 billion as of the end of the third quarter relative to $3.3 billion as of the end of the prior quarter.
Of the $3 billion in backlog, we expect approximately $380 million will convert into revenue in the fourth quarter.
Our net loss from continuing operations was $18.7 million or $0.28 per diluted share versus $13.3 million or $0.21 per diluted share in the prior year period.
Non-GAAP net income was $6.9 million versus $36.8 million in the prior year period, and non-GAAP diluted earnings per share was $0.10 versus $0.51 in the prior year period.
Mike will be taking on the role of President and Chief Operating Officer, effective upon the hiring of a new CFO.
At that point, he will transition to President and Chief Operating Officer.