[release/10.0] Fix GO batch separator not recognized when block comment contains single quote #37521

Copilot · 2026-01-16T00:12:15Z

Description

EF Core splits SQL Server migration scripts into batches on lines starting with GO. To avoid splitting inside string literals, SqlServerMigrationsSqlGenerator tracks whether it is inside a quoted string using a quoted boolean that toggles on single quotes ('). This quote-tracking logic was introduced in #34917.

The implementation does not handle standard SQL block comments (/* ... */). If a block comment contains a single quote, the quoted state is incorrectly toggled even though the quote is inside a comment. Since there is no matching closing quote, quoted remains true across subsequent lines. As a result, a later GO line is not recognized as a batch separator and is sent to SQL Server as literal text, causing:

Microsoft.Data.SqlClient.SqlException: Incorrect syntax near 'go'.

Customer impact

Customers using SQL migrations with stored procedures or other SQL scripts that include block comments containing single quotes will experience migration failures with "Incorrect syntax near 'go'" errors. This can occur when documentation comments in SQL scripts use contractions or possessives (e.g., "It's", "user's").

Workarounds:

Remove single quotes from block comments
Use two single quotes in block comments to escape them

How found

Customer reported on 10.0.1

Regression

Yes, from EF Core 9.0. Introduced in #34917.

Testing

Added 11 tests.

Risk

Medium. The changes only affect custom SQL operations in migrations.

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- Add tracking for block comments (/* ... */) to prevent incorrect quote state toggling - Block comments can now contain single quotes without affecting GO batch separator recognition - Add comprehensive tests for various block comment scenarios - All tests pass successfully Co-authored-by: AndriySvyryd <[email protected]>

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

Removed separate if statements and i++ increments. Block comment detection now integrated into the main switch statement, making the code cleaner and more maintainable. Co-authored-by: AndriySvyryd <[email protected]>

test/EFCore.SqlServer.FunctionalTests/Migrations/SqlServerMigrationsSqlGeneratorTest.cs

Added test to verify that /* inside a line comment (-- /*) doesn't trigger block comment state and GO is still correctly recognized as a batch separator. Co-authored-by: AndriySvyryd <[email protected]>

test/EFCore.SqlServer.FunctionalTests/Migrations/SqlServerMigrationsSqlGeneratorTest.cs

- Changed all GO to go in new test SQL strings (will still appear as GO in output) - Added test for multiline block comment with go on separate line to verify go inside block comments is correctly ignored Co-authored-by: AndriySvyryd <[email protected]>

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

Refactored to use foreach instead of for loop with index by tracking blockCommentStart and blockCommentEnd flags to detect /* and */ patterns across iterations. Co-authored-by: AndriySvyryd <[email protected]>

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

AndriySvyryd · 2026-01-16T22:10:05Z

@copilot Update progress by rewriting the PR summary using this template:

Fixes #{number}

**Description**
{Issue description}

**Customer impact**
{How does the reported issue affects customer's app? Are there workarounds?}

**How found**
{Was it customer reported or found during verification? How many customers are affected?}

**Regression**
{Is it a regression from a released version? Which one?}

**Testing**
{How the changes were tested}

**Risk**
{Low/Medium/High, argument why}

Removed comment "Fall through to process c with Normal state" as the fall-through behavior is self-evident from the code structure. Co-authored-by: AndriySvyryd <[email protected]>

Removed "Fall through to process c with Normal state" comment as the behavior is clear from the code structure. Co-authored-by: AndriySvyryd <[email protected]>

Copilot · 2026-01-16T22:19:48Z

@copilot Update progress by rewriting the PR summary using this template:

...

Done in 181fdd0. Updated PR description using the requested template format.

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

Removed redundant comments from Normal, Quoted, and InBlockComment cases that just stated "continue" as this behavior is self-evident from the break statements. Co-authored-by: AndriySvyryd <[email protected]>

Copilot

Pull request overview

This PR fixes a bug in SQL Server migrations where GO batch separators were not recognized when block comments contained single quotes. The issue was introduced in EF Core 9.0 when quote-tracking logic was added, but it didn't account for block comments.

Changes:

Replaces simple boolean quote tracking with a state machine that properly handles SQL strings, line comments, and block comments
Adds comprehensive test coverage with 11 new test cases covering various comment and string scenarios

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs	Implements a state machine with 6 states (Normal, Quoted, InBlockComment, MaybeLineComment, MaybeBlockCommentStart, MaybeBlockCommentEnd) to correctly parse SQL and ignore quotes inside block comments
test/EFCore.SqlServer.FunctionalTests/Migrations/SqlServerMigrationsSqlGeneratorTest.cs	Adds 11 test cases covering block comments with quotes, multiline comments, empty comments, nested comments/strings, and edge cases like GO inside comments

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

…r.cs Co-authored-by: Copilot <[email protected]>

artl93

@roji - With this being medium risk (though customer reported regression), is there an obvious workaround for the issue?

AndriySvyryd · 2026-01-20T20:24:46Z

@artl93 The workarounds are straightforward once the root cause is discovered, but since the exception is very sparse on details: Microsoft.Data.SqlClient.SqlException: Incorrect syntax near 'go'., it's far from obvious.
The reason this is medium risk is because the fix entails changes to a parser, so all the possible consequences aren't as clear.

artl93 · 2026-01-20T20:28:46Z

How can we reduce risk around the parser?

AndriySvyryd · 2026-01-20T20:30:59Z

How can we reduce risk around the parser?

I've added 11 new test cases. We could keep adding more

artl93

Obviously, we want to avoid regression. The more we can add, the better, but otherwise, approved.

roji · 2026-01-21T06:32:19Z

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

+            if (state == ParsingState.MaybeLineComment
+                || state == ParsingState.MaybeBlockCommentStart
+                || state == ParsingState.MaybeBlockCommentEnd)


Suggested change

if (state == ParsingState.MaybeLineComment

|| state == ParsingState.MaybeBlockCommentStart

|| state == ParsingState.MaybeBlockCommentEnd)

if (state is ParsingState.MaybeLineComment or ParsingState.MaybeBlockCommentStart or ParsingState.MaybeBlockCommentEnd)

roji · 2026-01-21T06:41:29Z

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

-                    switch (c)
+                    // Handle MaybeLineComment and MaybeBlockCommentStart first
+                    // When transitioning to Normal, fall through to process the current character
+                    if (state == ParsingState.MaybeLineComment)


IIUC the "Maybe" states are for multi-character tokens (--, /*), representing the state where we've seen the first character but not the second. If so, this can probably be considerably simplified by iterating over the characters with a for loop instead of a foreach, and then simply peeking ahead to look at the second character (*) when we're on the first (/). For example, this would obviate the Maybe states reset code code.

roji · 2026-01-21T06:42:25Z

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

-                    switch (c)
+                    // Handle MaybeLineComment and MaybeBlockCommentStart first
+                    // When transitioning to Normal, fall through to process the current character
+                    if (state == ParsingState.MaybeLineComment)


Also, any reason these two ifs aren't simply cases within the switch below?

roji · 2026-01-21T06:43:24Z

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

-                            commentStart = false;
+                        case ParsingState.Normal when c == '/':
+                            state = ParsingState.MaybeBlockCommentStart;
+                            break;


Can change to continue for (very) slight clarity.

roji · 2026-01-21T06:46:00Z

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

+                            state = ParsingState.MaybeBlockCommentStart;
+                            break;
+
+                        case ParsingState.Normal when c == '\'':


What about GO within square brackets and double quotes (like if the SQL script has INSERT INTO [GO] ...)?

roji · 2026-01-21T06:48:09Z

src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs

+                        state = ParsingState.Normal;
+                    }
+
+                    switch (state)


nit: consider changing this whole switch into a switch expression, where the default case simply returns the current state (i.e. no state change).

Initial plan

89d67fe

Copilot AI assigned Copilot and AndriySvyryd Jan 16, 2026

Copilot started work on behalf of AndriySvyryd January 16, 2026 00:12 View session

Copilot AI changed the title ~~[WIP] Fix GO batch separator recognition for block comments~~ Fix GO batch separator not recognized when block comment contains single quote Jan 16, 2026

Copilot AI requested a review from AndriySvyryd January 16, 2026 00:27

Copilot finished work on behalf of AndriySvyryd January 16, 2026 00:27

AndriySvyryd reviewed Jan 16, 2026

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src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs Outdated Show resolved Hide resolved

Copilot started work on behalf of AndriySvyryd January 16, 2026 00:32 View session

Refactor block comment handling to combine with switch statement

4995896

Removed separate if statements and i++ increments. Block comment detection now integrated into the main switch statement, making the code cleaner and more maintainable. Co-authored-by: AndriySvyryd <[email protected]>

Copilot AI requested a review from AndriySvyryd January 16, 2026 00:40

Copilot finished work on behalf of AndriySvyryd January 16, 2026 00:40

AndriySvyryd reviewed Jan 16, 2026

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test/EFCore.SqlServer.FunctionalTests/Migrations/SqlServerMigrationsSqlGeneratorTest.cs Show resolved Hide resolved

Copilot started work on behalf of AndriySvyryd January 16, 2026 00:53 View session

Add test for line comment containing block comment start before GO

672fa56

Added test to verify that /* inside a line comment (-- /*) doesn't trigger block comment state and GO is still correctly recognized as a batch separator. Co-authored-by: AndriySvyryd <[email protected]>

Copilot AI requested a review from AndriySvyryd January 16, 2026 01:01

Copilot finished work on behalf of AndriySvyryd January 16, 2026 01:01

AndriySvyryd reviewed Jan 16, 2026

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test/EFCore.SqlServer.FunctionalTests/Migrations/SqlServerMigrationsSqlGeneratorTest.cs Show resolved Hide resolved

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Copilot AI requested a review from AndriySvyryd January 16, 2026 01:41

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src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerator.cs Outdated Show resolved Hide resolved

Copilot started work on behalf of AndriySvyryd January 16, 2026 01:46 View session

Change back to foreach for character iteration

da14de3

Refactored to use foreach instead of for loop with index by tracking blockCommentStart and blockCommentEnd flags to detect /* and */ patterns across iterations. Co-authored-by: AndriySvyryd <[email protected]>

Copilot AI requested a review from AndriySvyryd January 16, 2026 01:54

Copilot finished work on behalf of AndriySvyryd January 16, 2026 01:54

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Copilot started work on behalf of AndriySvyryd January 16, 2026 22:09 View session

Remove unnecessary comment from state transition

c037138

Removed comment "Fall through to process c with Normal state" as the fall-through behavior is self-evident from the code structure. Co-authored-by: AndriySvyryd <[email protected]>

Copilot AI requested a review from AndriySvyryd January 16, 2026 22:14

Copilot finished work on behalf of AndriySvyryd January 16, 2026 22:14

Copilot started work on behalf of AndriySvyryd January 16, 2026 22:15 View session

Remove comment from state transition logic

181fdd0

Removed "Fall through to process c with Normal state" comment as the behavior is clear from the code structure. Co-authored-by: AndriySvyryd <[email protected]>

Copilot finished work on behalf of AndriySvyryd January 16, 2026 22:20

AndriySvyryd changed the title ~~Fix GO batch separator not recognized when block comment contains single quote~~ [release/10.0] Fix GO batch separator not recognized when block comment contains single quote Jan 16, 2026

AndriySvyryd reviewed Jan 16, 2026

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Copilot started work on behalf of AndriySvyryd January 16, 2026 23:38 View session

Remove unnecessary comments from state handling switch

b60e053

Removed redundant comments from Normal, Quoted, and InBlockComment cases that just stated "continue" as this behavior is self-evident from the break statements. Co-authored-by: AndriySvyryd <[email protected]>

Copilot AI requested a review from AndriySvyryd January 16, 2026 23:44

Copilot finished work on behalf of AndriySvyryd January 16, 2026 23:44

AndriySvyryd marked this pull request as ready for review January 16, 2026 23:46

AndriySvyryd requested a review from a team as a code owner January 16, 2026 23:46

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Update src/EFCore.SqlServer/Migrations/SqlServerMigrationsSqlGenerato…

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…r.cs Co-authored-by: Copilot <[email protected]>

artl93 reviewed Jan 20, 2026

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artl93 approved these changes Jan 20, 2026

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roji reviewed Jan 21, 2026

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[release/10.0] Fix GO batch separator not recognized when block comment contains single quote #37521

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