dotnet/efcore · error · NotSupportedException

LINQ query comprehension syntax is currently not supported i

Error message

LINQ query comprehension syntax is currently not supported in precompiled queries.

What it means

VisitQueryExpression throws NotSupportedException for C# LINQ query comprehension syntax (from ... where ... select). Precompiled queries only support the method-based LINQ syntax that maps to expression-tree-building extension methods; query comprehension is an explicit, documented limitation.

Source

Thrown at src/EFCore.Design/Query/Internal/CSharpToLinqTranslator.cs:990

            SyntaxKind.PostDecrementExpression => throw NotSupportedInExpressionTrees(),

            _ => throw new UnreachableException(
                $"Unexpected syntax kind '{unary.Kind()}' when visiting a {nameof(PostfixUnaryExpressionSyntax)}")
        };

        NotSupportedException NotSupportedInExpressionTrees()
            => throw new UnreachableException(
                $"Unary expression of type {unary.Kind()} is not supported in expression trees");
    }

    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that
    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
    /// </summary>
    public override Expression VisitQueryExpression(QueryExpressionSyntax node)
        => throw new NotSupportedException(DesignStrings.QueryComprehensionSyntaxNotSupportedInPrecompiledQueries);

    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that
    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
    /// </summary>
    public override Expression VisitSimpleLambdaExpression(SimpleLambdaExpressionSyntax lambda)
        => VisitLambdaExpression(lambda);

    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that
    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
    /// </summary>
    public override Expression VisitTypeOfExpression(TypeOfExpressionSyntax typeOf)
    {

View on GitHub (pinned to dbf9771522)

Solutions

Rewrite the query using method syntax with lambda expressions
Convert each clause: from/where -> .Where, orderby -> .OrderBy, select -> .Select

Example fix

// before
from b in ctx.Blogs
where b.Active
select b
// after
ctx.Blogs.Where(b => b.Active)

Defensive patterns

Strategy: validation

Validate before calling

// Detect query comprehension syntax in precompiled query source.
static bool UsesQuerySyntax(string src)
    => System.Text.RegularExpressions.Regex.IsMatch(src, @"\b(from|select|orderby|group\s+by|join)\b");
if (UsesQuerySyntax(querySource)) { /* rewrite to method syntax */ }

Prevention

Always write precompiled queries in method syntax (.Where/.Select/.OrderBy)
Convert query-syntax examples before pasting them into a precompiled query
Enable an analyzer/roslynator rule to flag query syntax in precompiled query files

When it happens

Trigger: Writing a precompiled query using SQL-like query syntax: from b in ctx.Blogs where b.Active orderby b.Name select b.

Common situations: Developers who prefer SQL-like LINQ syntax or paste query-syntax examples into a precompiled query.

Related errors

AI-assisted analysis of dotnet/efcore@dbf9771522 (2026-08-06). Data as JSON: /api/errors/94fca48f1937cb41. Report an issue: GitHub.