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[master] [Subscription Billing] Infinite loop in CalculateBillingPeriod when HarmonizeNextBillingTo caps at stale "Next Billing To" date #8830

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[master] [Subscription Billing] Infinite loop in CalculateBillingPeriod when HarmonizeNextBillingTo caps at stale "Next Billing To" date #8830

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c6fdb4c
Added Fix
sanjmaurya Jun 26, 2026
1214474
Added Test
sanjmaurya Jun 26, 2026
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9 changes: 7 additions & 2 deletions src/Apps/W1/Subscription Billing/App/Billing/Codeunits/BillingProposal.Codeunit.al
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Original file line number Diff line number Diff line change
Expand Up @@ -483,6 +483,7 @@ codeunit 8062 "Billing Proposal"
local procedure CalculateBillingPeriod(ServiceCommitment: Record "Subscription Line"; BillingDate: Date; BillToDate: Date; var BillingPeriodStart: Date; var BillingPeriodEnd: Date)
var
UsageDataBilling: Record "Usage Data Billing";
PreviousBillingPeriodEnd: Date;
begin
BillingPeriodEnd := 0D;
BillingPeriodStart := ServiceCommitment."Next Billing Date";
Expand All @@ -505,10 +506,14 @@ codeunit 8062 "Billing Proposal"
end;

BillingPeriodEnd := CalculateNextBillingToDateForServiceCommitment(ServiceCommitment, BillingPeriodStart);
PreviousBillingPeriodEnd := 0D;
while (BillingPeriodEnd < BillingDate) and
((BillingPeriodEnd < ServiceCommitment."Subscription Line End Date") or (ServiceCommitment."Subscription Line End Date" = 0D))
do

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$\textbf{🟡\ Medium\ Severity\ —\ Agent} \quad \color{gray}{\texttt{\small Iteration\ 1}}$

The new loop-progress guard (BillingPeriodEnd > PreviousBillingPeriodEnd) correctly prevents an infinite loop, but when it fires it exits silently: the var output parameter BillingPeriodEnd is left holding the non-advancing value returned by CalculateNextBillingToDateForServiceCommitment, and the caller receives no signal distinguishing a normal exit (billing date or end-date boundary reached) from an abnormal one (the inner function failed to advance the period).

In subscription billing, a silently incorrect BillingPeriodEnd can produce wrong invoice amounts or missed billing lines.

Recommendation:

  • after the loop, detect the abnormal case — for example by checking whether the guard condition would have allowed another iteration but didn't — and raise an Error or emit a telemetry signal so the failure surface is observable.

👍 useful · ❤️ especially valuable · 👎 wrong - reply with why

((BillingPeriodEnd < ServiceCommitment."Subscription Line End Date") or (ServiceCommitment."Subscription Line End Date" = 0D)) and
(BillingPeriodEnd > PreviousBillingPeriodEnd)
do begin
PreviousBillingPeriodEnd := BillingPeriodEnd;
BillingPeriodEnd := CalculateNextBillingToDateForServiceCommitment(ServiceCommitment, BillingPeriodEnd + 1);
end;
end;

procedure CalculateNextBillingToDateForServiceCommitment(ServiceCommitment: Record "Subscription Line"; BillingFromDate: Date) NextBillingToDate: Date
Expand Down
44 changes: 44 additions & 0 deletions src/Apps/W1/Subscription Billing/Test/Billing/RecurringBillingTest.Codeunit.al
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Expand Up @@ -68,6 +68,7 @@ codeunit 139688 "Recurring Billing Test"
PostedDocumentNo: Code[20];
StrMenuHandlerStep: Integer;
BillingProposalNotCreatedErr: Label 'Billing proposal not created.', Locked = true;
BillingToCappedErr: Label 'Billing to should be capped at the harmonized Next Billing To date.', Locked = true;
ExtendedTextValueErr: Label 'Sales line with extended text description should be created.', Locked = true;
ExtendedTextPurchValueErr: Label 'Purchase line with extended text description should be created.', Locked = true;
RecurringBillingPage: TestPage "Recurring Billing";
Expand Down Expand Up @@ -1571,6 +1572,49 @@ codeunit 139688 "Recurring Billing Test"
Assert.AreEqual(ExpectedNextBillingDate, ServiceCommitment."Next Billing Date", 'Next Billing Date should be the day after the last Billing To date.');
end;

[Test]
procedure CreateBillingProposalForHarmonizedContractWithCappedNextBillingToDoesNotHang()
var
ContractType: Record "Subscription Contract Type";
BillingDate: Date;
CappedNextBillingTo: Date;
begin
// [SCENARIO 637042] Creating a Billing Proposal for a harmonized billing contract must not hang when the contract "Next Billing To" caps the calculated billing period below the Billing Date
Initialize();

// [GIVEN] An LCY Customer Subscription Contract with a monthly Subscription Line
CreateCustomerContract('<1M>', '<12M>');
FindFirstServiceCommitment();

// [GIVEN] The contract uses a harmonized billing contract type
ContractTestLibrary.CreateContractType(ContractType);
ContractType.HarmonizedBillingCustContracts := true;
ContractType.Modify(false);

// [GIVEN] The harmonized "Next Billing To" is frozen at the first billing period end, which is earlier than the Billing Date
CappedNextBillingTo := ServiceCommitment.CalculateNextToDate(ServiceCommitment."Billing Rhythm", ServiceCommitment."Next Billing Date");
BillingDate := CalcDate('<+6M>', ServiceCommitment."Next Billing Date");
CustomerContract.Get(CustomerContract."No.");
CustomerContract."Contract Type" := ContractType.Code;
CustomerContract."Next Billing To" := CappedNextBillingTo;
CustomerContract.Modify(false);

// [GIVEN] A Billing Template filtered on the harmonized contract
CustomerContract.SetRecFilter();
ContractTestLibrary.CreateRecurringBillingTemplate(BillingTemplate, '', '', CustomerContract.GetView(), Enum::"Service Partner"::Customer);

// [WHEN] Create Billing Proposal up to a Billing Date that lies beyond the frozen "Next Billing To"
// [THEN] The process completes without entering an infinite loop in CalculateBillingPeriod (before the fix it would spin until a SQL timeout)
ContractTestLibrary.CreateBillingProposal(BillingTemplate, Enum::"Service Partner"::Customer, BillingDate, 0D);

// [THEN] A Billing Line is created and its "Billing to" is capped at the harmonized "Next Billing To" date
BillingLine.Reset();
BillingLine.SetRange("Subscription Contract No.", CustomerContract."No.");
Assert.RecordIsNotEmpty(BillingLine);
BillingLine.FindLast();
Assert.AreEqual(CappedNextBillingTo, BillingLine."Billing to", BillingToCappedErr);
end;

#endregion Tests

#region Procedures
Expand Down
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