An Exception Running Zcash 1.0.0

On Ubuntu 16.04.1 64-bit with Zcash 1.0.0 I get this error:

EXCEPTION: St13runtime_error

CDB() : can't open database
Zcash in AppInit()

is there anyone who help me out?

you'll have to be a bit more verbose. what was the command you entered? what did debug.log put?

I typed the command ./src/zcasd. Then after some minutes,the error was displayed. the debug.log was put in the directory .zcash

get the contents of debug.log wherever the dot dir - ala .zcash

cat [DOT DIR LOCATION].zcash/debug.log

I did it as you said. After the command, the outcome was five pieces of information,as follows:

2016-10-31 07:38:40 scheduler thread interrupt
2016-10-31 07:38:40 Shutdown: In progress...
2016-10-31 07:38:40 RPCAcceptHandler: Error: Operation canceled
2016-10-31 07:38:40 RPCAcceptHandler: Error: Operation canceled
2016-10-31 07:38:40 StopRPCThreads: waiting for async rpc workers to stop
2016-10-31 07:38:40 StopNode()
2016-10-31 07:38:40 Shutdown :done

the first line is a thread interrupt occurring within the boost library.
realize you've already said this is 1.0.0, but can you verify the branch in which you built zcash:

$ cd [zcash git repo]; git branch -v

after operating the instruction, two lines are followd:
1feaefa Update network magics for 1.0.0
master 1feaefa Update network magics for 1.0.0.

there are some words in the first line's front,roughly speaking,the head pointer seperated from v1.0.0

yeah you didn't checkout v1.0.0 branch and are still in master.
see https://github.com/zcash/zcash/wiki/1.0-User-Guide

but .. but it was successful at one time. Later,it crashed, and exception came out.

Moreover, I executed git checkout v1.0.0

right but the put of current branch you shared said otherwise...

Oh, I am wondering what should I do now? follow your link posted, do the instructions again from scratch?

string the elf

$ if [ `strings src/zcashd|grep -c 'v1.0.0'` != 0 ]; then echo '42'; fi

if you get a 42, we can wholeheartedly verify that this build is in fact v1.0.0.
otherwise - yes no one wants to - but you'll have to follow through those instructions again and build from scratch :joy:

I want to know whether my previous Zcash information will be useless if I compile&install again´╝č

If you've made any transactions, or have mined any zcash prior, yes back up your wallet https://forum.zcashcommunity.com/t/wallet-dat-private-key-z-t-addresses-what-to-backup/4506/3 before reinstall.