Question: input: Article: The figures have been released by HM Crown Prosecution Service Inspectorate.
Defendants can be acquitted or see their trials rescheduled in such cases.
But the HMCPSI said too many domestic violence case witnesses were summonsed, which risked "alienating" victims who were willing to give evidence.
In 2014-15, for a various of reasons, more than half of the 195,000 trials listed in magistrates and crown courts did not go ahead as planned, the report said.
Failure to appear could result in a warrant for the witness's arrest.
The inspectorate found a rising number of prosecutions were "cracked" - which is the term used for a case that closes unexpectedly because a witness is absent or has withdrawn evidence.
This happened in nearly 800 crown court trials and in 10,600 hearings in magistrates' courts.
The report said that 2.1% of trials in the crown court and 6.8% of trials in the magistrates' court were "cracked" in 2014-15, compared with 1.8% and 6.3% respectively the previous year.
The inspectorate said a "powerful tool" to persuade someone to testify was a summons which makes attendance a legal requirement.
But it said summonses were being used inappropriately for more than one in 10 witnesses in domestic abuse cases.
Chief inspector of the HMCPSI Kevin McGinty said: "The CPS [Crown Prosecution Service] rightly wants to reduce the number of times that trials have to be rescheduled or defendants walking free, but there's little evidence that use of the summons is making a difference."
An HMCPSI spokesman added: "A witness summons is the last resort for those who disengage from a prosecution and should only be considered when all other avenues have been exhausted."
A Crown Prosecution Service spokesman said that along with police it was conducting a joint review of the provision of support to victims and witnesses.
"This review, which aims to improve levels of service, will be an opportunity to explore the reasons for the drop in witness attendance," he added.
"We will be updating our training on domestic abuse over 2016-17 and will consider including training on witness summonses within this."

Summarize.
output: More than 11,000 criminal trials in England and Wales had to be abandoned last year because witnesses pulled out or did not appear at court, a watchdog has said.
Article: Nick Corsellis, lawyer for Carl Wood, said an "inside man" must have been involved in the raid but his client lacked the expertise to be that person.
Mr Wood and three other men deny taking part in the Â£14m heist.
Four others have already pleaded guilty for their roles in the robbery.
During his closing speech, Mr Corsellis told Woolwich Crown Court the gang were "serious organised criminals" who had put a team together where "each member has to have a role".
"And this is one of the reasons Mr Wood is not guilty. What did he bring to the table?" he said.
Mr Corsellis said it did not follow that his client was the man identified by the prosecution as "Man F" in CCTV footage of the raid.
"Male F was actually a player. An inside man, or linked to the inside man, fully familiar with the inner workings of Hatton Garden Safe Deposit".
Mr Wood lacked such knowledge and would have only been able to act as a "general dogsbody", the lawyer said.
Mr Corsellis asked the jury whether professional criminals would have been prepared to give up part of their millions to a person who would have only been an "extra pair of hands (EPH)".
He called it "illogical" and "implausible" that such a person was involved as "criminals are not charitable people".
Speaking about how the prosecution had said the heist could be turned into a TV programme or film, Mr Corsellis suggested movie titles could include "Bad Grandpas" or "The Enfield Expendables".
"But who would play Carl Wood - the EPH? Do you think Mr Tom Hardy or Mr Vinnie Jones is going to rush to take the part of... the EPH?" he asked.
The case continues.
Daniel Jones, 60, of Park Avenue, Enfield; John Collins, 75, of Bletsoe Walk, Islington; Terry Perkins, 67, of Heene Road, Enfield, and Brian Reader, 76, of Dartford Road, Dartford, have all previously pleaded guilty to conspiracy to commit burglary.
++++++++++
Summarize: One of the men accused of being part of the Hatton Garden raid could not have been involved because he lacked any skill to offer the gang, a court has heard.
Question:
Article:More than three million people are estimated to have gathered for the service in the city of Rio de Janeiro.
Many of the pilgrims had slept on the beach after attending an all-night vigil, also led by Pope Francis.
Sunday's ceremony marks the end of the Pope's five-day visit to Brazil - his first foreign trip since becoming pontiff in March.
He flew back to Rome late on Sunday.
The BBC's Wyre Davies in Rio says almost every inch of the two-and-a-half mile long beach was occupied ahead of the Mass, as most of the young people stayed after the  vigil, pitching tents or sleeping in the open.
The vigil and Sunday mass attracted the biggest crowd ever to Copacabana beach, which has hosted rock concerts, sports events and the traditional New Year celebrations.
Pope Francis encouraged young Catholics to get out of their parochial boundaries in order to help others.
"Go and don't be afraid of serving," he said.
"Jesus did not gather the Apostles so they lived in isolation. He called them so they formed a group, a community," said Pope Francis.
He announced the next Catholic youth festival would be held in the Polish city of Krakow in 2016.
Female activists held a demonstration nearby in support of abortion and women's rights.
But our correspondent says the Pope and the Church hierarchy will be delighted at the huge turnout and the way Francis has been received by pilgrims from across the globe.
In the past three decades, the Catholic church has lost millions of followers to smaller Christian denominations.
In his vigil address on Saturday, the pontiff had urged the pilgrims not to be "part-time Christians", but to lead full, meaningful lives.
Speaking on a huge stage at the beach where a mock church structure was built, Pope Francis referred to the street protests which have been taking place in Brazil for more than a month.
"The young people in the street are the ones who want to be actors of  change. Please don't let others be actors of change," he told the crowd at the vigil.
"Keep overcoming apathy and offering a Christian response to the social and political concerns taking place in  different parts of the world."
Also on Saturday, the Pope repeated his challenge to fellow Roman Catholic clerics to take to the streets.
In a speech to 1,000 bishops and clerics in Rio's cathedral, he said they should go to the favelas - Brazil's shanty towns.
"We cannot keep ourselves shut up in parishes, in our communities, when so many people are waiting for the Gospel," he told the audience.
Protests, sometimes violent, broke out in cities across Brazil last month against corruption, poor public services and the high cost of events like the 2014 World Cup.

Summarize the main points of that article.
Answer:

Answer: Pope Francis has closed one of the biggest Roman Catholic youth festivals with a Mass on Copacabana beach.