diff --git a/.gitignore b/.gitignore
index 503a4e114..9801ed968 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,4 @@ dist
 *.db-journal
 *.tgz
 .pnpm-store
+*.vsix
diff --git a/packages/language/src/validators/expression-validator.ts b/packages/language/src/validators/expression-validator.ts
index f455753f8..c2848c145 100644
--- a/packages/language/src/validators/expression-validator.ts
+++ b/packages/language/src/validators/expression-validator.ts
@@ -12,6 +12,7 @@ import {
     isReferenceExpr,
     isThisExpr,
     MemberAccessExpr,
+    UnaryExpr,
     type ExpressionType,
 } from '../generated/ast';
 
@@ -67,6 +68,9 @@ export default class ExpressionValidator implements AstValidator<Expression> {
             case 'BinaryExpr':
                 this.validateBinaryExpr(expr, accept);
                 break;
+            case 'UnaryExpr':
+                this.validateUnaryExpr(expr, accept);
+                break;
         }
     }
 
@@ -245,6 +249,12 @@ export default class ExpressionValidator implements AstValidator<Expression> {
         }
     }
 
+    private validateUnaryExpr(expr: UnaryExpr, accept: ValidationAcceptor) {
+        if (expr.operand.$resolvedType && expr.operand.$resolvedType.decl !== 'Boolean') {
+            accept('error', `operand of "${expr.operator}" must be of Boolean type`, { node: expr.operand });
+        }
+    }
+
     private validateCollectionPredicate(expr: BinaryExpr, accept: ValidationAcceptor) {
         if (!expr.$resolvedType) {
             accept('error', 'collection predicate can only be used on an array of model type', { node: expr });
diff --git a/packages/orm/src/client/executor/zenstack-query-executor.ts b/packages/orm/src/client/executor/zenstack-query-executor.ts
index 201c3229f..6c1cbd5e9 100644
--- a/packages/orm/src/client/executor/zenstack-query-executor.ts
+++ b/packages/orm/src/client/executor/zenstack-query-executor.ts
@@ -198,7 +198,7 @@ export class ZenStackQueryExecutor extends DefaultQueryExecutor {
             if (parameters) {
                 compiled = { ...compiled, parameters };
             }
-            return connection.executeQuery<any>(compiled);
+            return this.internalExecuteQuery(connection, compiled);
         }
 
         if (
@@ -246,7 +246,7 @@ export class ZenStackQueryExecutor extends DefaultQueryExecutor {
             queryId,
         );
 
-        const result = await connection.executeQuery<any>(compiled);
+        const result = await this.internalExecuteQuery(connection, compiled);
 
         if (!this.driver.isTransactionConnection(connection)) {
             // not in a transaction, just call all after-mutation hooks
@@ -470,7 +470,7 @@ export class ZenStackQueryExecutor extends DefaultQueryExecutor {
         const compiled = this.compileQuery(selectQueryNode, createQueryId());
         // execute the query directly with the given connection to avoid triggering
         // any other side effects
-        const result = await connection.executeQuery(compiled);
+        const result = await this.internalExecuteQuery(connection, compiled);
         return result.rows as Record<string, unknown>[];
     }
 
@@ -483,4 +483,12 @@ export class ZenStackQueryExecutor extends DefaultQueryExecutor {
             return condition2;
         }
     }
+
+    private async internalExecuteQuery(connection: DatabaseConnection, compiledQuery: CompiledQuery) {
+        try {
+            return await connection.executeQuery<any>(compiledQuery);
+        } catch (err) {
+            throw createDBQueryError('Failed to execute query', err, compiledQuery.sql, compiledQuery.parameters);
+        }
+    }
 }
diff --git a/tests/regression/test/issue-503/regression.test.ts b/tests/regression/test/issue-503/regression.test.ts
index c31864a70..e901ce426 100644
--- a/tests/regression/test/issue-503/regression.test.ts
+++ b/tests/regression/test/issue-503/regression.test.ts
@@ -2,7 +2,7 @@ import { createTestClient } from '@zenstackhq/testtools';
 import { describe, expect, it } from 'vitest';
 import { schema } from './schema';
 
-describe('Regression tests for issues #503', () => {
+describe('Regression tests for issue #503', () => {
     it('verifies the issue', async () => {
         const db = await createTestClient(schema);
         const r = await db.internalChat.create({
diff --git a/tests/regression/test/issue-505.test.ts b/tests/regression/test/issue-505.test.ts
index da8482857..bbbca26c9 100644
--- a/tests/regression/test/issue-505.test.ts
+++ b/tests/regression/test/issue-505.test.ts
@@ -1,7 +1,7 @@
 import { createTestClient } from '@zenstackhq/testtools';
 import { describe, expect, it } from 'vitest';
 
-describe('Regression tests for issues 505', () => {
+describe('Regression tests for issue 505', () => {
     it('verifies the issue', async () => {
         const db = await createTestClient(
             `
diff --git a/tests/regression/test/issue-510.test.ts b/tests/regression/test/issue-510.test.ts
new file mode 100644
index 000000000..1816fe824
--- /dev/null
+++ b/tests/regression/test/issue-510.test.ts
@@ -0,0 +1,103 @@
+import { createPolicyTestClient } from '@zenstackhq/testtools';
+import { describe, expect, it } from 'vitest';
+
+describe('Regression tests for issue 510', () => {
+    it('verifies the issue', async () => {
+        const schema = `
+type ID {
+    id String @id @default(nanoid())
+}
+
+type Timestamps {
+    createdAt DateTime @default(now())
+    updatedAt DateTime @updatedAt
+}
+
+type Base with ID, Timestamps {
+}
+
+type AuthInfo {
+    id       String
+    username String
+    role     Role
+
+    @@auth
+}
+
+enum Role {
+    SUPERADMIN
+    ADMIN
+    USER
+}
+
+enum FileStatus {
+    PENDING
+    UPLOADED
+    FAILED
+}
+
+model User with Base {
+    username     String         @unique
+    passwordHash String
+    name         String
+    role         Role
+
+    RefreshToken RefreshToken[]
+    File         File[]
+    Post         Post[]
+
+    @@allow('all', auth().id == id)
+}
+
+model File with Timestamps {
+    key              String     @id
+
+    userId           String
+    User             User       @relation(fields: [userId], references: [id])
+
+    originalFilename String
+    filename         String
+    contentType      String
+    size             Int?
+    status           FileStatus
+
+    Post             Post[]
+
+    @@allow('all', auth().id == userId)
+}
+
+model AuditLog {
+    timestamp DateTime @id @default(now())
+
+    action    String
+    data      Json
+
+    @@deny('all', true)
+}
+
+model RefreshToken with Base {
+    userId  String
+    User    User    @relation(fields: [userId], references: [id])
+
+    revoked Boolean
+
+    @@deny('all', true)
+}
+
+model Post with Base {
+    userId   String
+    User     User    @relation(fields: [userId], references: [id])
+
+    content  String
+    imageKey String?
+    Image    File?   @relation(fields: [imageKey], references: [key])
+
+    @@allow('read', true)
+    @@allow('create', auth().id == userId && (!Image || auth().id == Image.userId))
+    @@allow('update,delete', auth().id == userId)
+}
+`;
+
+        await expect(createPolicyTestClient(schema)).rejects.toThrow(/operand of "!" must be of Boolean type/);
+    });
+});