c# - An exception of type 'System.ArgumentOutOfRangeException' occurred in mscorlib.dll but was not handled in user code -

i have console application generates set of fake data/information on database testing.

public list<lcs_exchangedatastaging> generatenewdata(int count)             {                 var newdata = new list<lcs_exchangedatastaging>();                 var random = new random();                 var branches = new lcsbranchcontext().getallbranches();                 var schemeids = new lcsschemeportfoliocontext().schemeportfolios();              var branchcount = branches.count - 1;             var schemecount = schemeids.count - 1;              parallel.for(1, count + 1, =>             {                 int gender = random.next(0, 1);                  var data = new lcs_exchangedatastaging                 {                     accountnumber = (3000000000 + random.next(999999999)).tostring(),                     accountstatement = random.next(),                     address = faker.address.streetaddress(),                     addressofkeycontact = faker.address.streetaddress(),                     age = randomdate(datetime.now.addyears(-70), datetime.now.addyears(-18), random),                     amountdisbursed = faker.randomnumber.next(20000000),                     amountoverdue = faker.randomnumber.next(1000000),                     branchname = branches[random.next(branchcount)].name,                     clientid = $"r{(faker.randomnumber.next(99999999) + 200000000).tostring()}",                     clientname = gender == 0 ? namegenerator.generate(gender.male) : namegenerator.generate(gender.female),                     companiesmandate = "",                     dateofincorporation = randomdate(datetime.now.addyears(-70), datetime.now, random),                     dayspastdue = 1,                     disbursmentdate = randomdate(datetime.now.addyears(-3), datetime.now, random),                     email = faker.internet.email(),                     emergencycontact = faker.name.fullname(),                     employeecontact = faker.name.fullname(),                     employeecontacttelephone = faker.phone.number(),                     employeraddress = faker.address.streetaddress(),                     employername = faker.company.name(),                     employertelephone = faker.phone.number(),                     expirydate = randomdate(datetime.now.addyears(1), datetime.now.addyears(7), random),                     feesoverdue = faker.randomnumber.next(2000),                     gender = gender == 0 ? "m" : "f",                     guarantoraddress = faker.address.streetaddress(),                     guarantorname = faker.name.fullname(),                     guarantortelephone = faker.phone.number(),                     income = random.next(50000, 1000000),                     insurancecompany = faker.company.name(),                     insuredamount = faker.randomnumber.next(2000),                     interestrate = random.next(3, 24),                     intrduceraddress = faker.address.streetaddress(),                     intrestoverdue = faker.randomnumber.next(2000),                     introducername = faker.name.fullname(),                     introducertelephone = faker.phone.number(),                     keycontactperson = faker.name.fullname(),                     lastcramount = faker.randomnumber.next(20000),                     lastcrdate = randomdate(datetime.now.addyears(-1), datetime.now, random),                     lienamount = faker.randomnumber.next(2000),                     loanrestructured = "no",                     missedpayin24monthcount = random.next(0, 15),                     monthlyinflow = faker.randomnumber.next(1000000),                     operativeaccountnumber = $"01{random.next(99999999)}",                     outstandingprincipal = faker.randomnumber.next(200000),                     penalchargedue = faker.randomnumber.next(2000),                     principaloverdue = faker.randomnumber.next(2000),                     productcategory = "",                     producttype = "laa",                     relationshipyears = random.next(0, 40),                     repaymentamount = faker.randomnumber.next(2000),                     returnedchequein6monthcount = random.next(0, 3),                     schemeid = schemeids[random.next(schemecount)].schemecode,                     telephone1 = faker.phone.number(),                     telephone2 = faker.phone.number(),                     telephoneofkeycontact = faker.phone.number(),                     tenor = random.next(3, 124).tostring(),                 };                  newdata.add(data);             });              return newdata;         } 

however, when method generatenewdata runs, exception

an exception of type 'system.argumentoutofrangeexception' occurred in mscorlib.dll not handled in user code

additional information: 'maxvalue' must greater zero.

system.argumentoutofrangeexception unhandled user code   hresult=-2146233086   message='maxvalue' must greater zero. parameter name: maxvalue   paramname=maxvalue   source=mscorlib   stacktrace:        @ system.random.next(int32 maxvalue)        @ rlcs.tasks.data.datagenerator.<>c__displayclass1_0.<generatenewdata>b__0(int32 i) in c:\users\solution architect\documents\work\lcs\lcs\rlcs.tasks\data\datagenerator.cs:line 50        @ system.threading.tasks.parallel.<>c__displayclass17_0`1.<forworker>b__1()   innerexception: 

please suggestions might have on this. thanks

it's hard tell without running or seeing of code, problem 1 of calls random.next(int32 maxvalue) providing int32 maxvalue of 0 or less. narrows down 1 of following lines -

branchname = branches[random.next(branchcount)].name,

schemeid = schemeids[random.next(schemecount)].schemecode,

so important variables seem branchcount , schemecount. these set count - 1 of respective context method results.

i suspect either lcsbranchcontext().getallbranches() or lcsschemeportfoliocontext().schemeportfolios() returning 1 or 0 results, can "fix" making them return more results, better solution use faker.random.listitem() , c# 6 safe navigation operator (?) -

branchname = faker.random.listitem(branches)?.name,

schemeid = faker.random.listitem(schemeids)?.schemecode,

which set value null if there aren't entries in provided list.

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