diff --git a/.changeset/clean-fans-wait.md b/.changeset/clean-fans-wait.md
new file mode 100644
index 00000000000..116f568c691
--- /dev/null
+++ b/.changeset/clean-fans-wait.md
@@ -0,0 +1,5 @@
+---
+"fuels": patch
+---
+
+fix: replace the outdated `--manual_blocks_enabled` flag with `--debug` (fuel-core)
diff --git a/packages/fuels/src/cli/commands/dev/startFuelCore.ts b/packages/fuels/src/cli/commands/dev/startFuelCore.ts
index 58d0d314470..ac12446876a 100644
--- a/packages/fuels/src/cli/commands/dev/startFuelCore.ts
+++ b/packages/fuels/src/cli/commands/dev/startFuelCore.ts
@@ -69,7 +69,7 @@ export const startFuelCore = async (config: FuelsConfig): Promise<FuelCoreNode>
     ['--chain', chainConfig],
     '--vm-backtrace',
     '--utxo-validation',
-    '--manual_blocks_enabled',
+    '--debug',
   ].flat();
 
   return new Promise((resolve, reject) => {