diff --git a/core/src/main/java/google/registry/env/production/backend/WEB-INF/appengine-web.xml b/core/src/main/java/google/registry/env/production/backend/WEB-INF/appengine-web.xml
index e59cb166e6..fb2c17152d 100644
--- a/core/src/main/java/google/registry/env/production/backend/WEB-INF/appengine-web.xml
+++ b/core/src/main/java/google/registry/env/production/backend/WEB-INF/appengine-web.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
+  <runtime>java8</runtime>
   <service>backend</service>
-  <app-engine-apis>true</app-engine-apis>
+  <!--app-engine-apis>true</app-engine-apis-->
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <basic-scaling>
diff --git a/core/src/main/java/google/registry/env/production/default/WEB-INF/appengine-web.xml b/core/src/main/java/google/registry/env/production/default/WEB-INF/appengine-web.xml
index 44b867b5ea..a72a531f22 100644
--- a/core/src/main/java/google/registry/env/production/default/WEB-INF/appengine-web.xml
+++ b/core/src/main/java/google/registry/env/production/default/WEB-INF/appengine-web.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
+  <runtime>java8</runtime>
   <service>default</service>
-  <app-engine-apis>true</app-engine-apis>
+  <!--app-engine-apis>true</app-engine-apis-->
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <manual-scaling>
diff --git a/core/src/main/java/google/registry/env/production/pubapi/WEB-INF/appengine-web.xml b/core/src/main/java/google/registry/env/production/pubapi/WEB-INF/appengine-web.xml
index 22922a18f3..63d36620ab 100644
--- a/core/src/main/java/google/registry/env/production/pubapi/WEB-INF/appengine-web.xml
+++ b/core/src/main/java/google/registry/env/production/pubapi/WEB-INF/appengine-web.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
+  <runtime>java8</runtime>
   <service>pubapi</service>
-  <app-engine-apis>true</app-engine-apis>
+  <!--app-engine-apis>true</app-engine-apis-->
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <manual-scaling>
diff --git a/core/src/main/java/google/registry/env/production/tools/WEB-INF/appengine-web.xml b/core/src/main/java/google/registry/env/production/tools/WEB-INF/appengine-web.xml
index bdacaa04cf..3c7e5e627c 100644
--- a/core/src/main/java/google/registry/env/production/tools/WEB-INF/appengine-web.xml
+++ b/core/src/main/java/google/registry/env/production/tools/WEB-INF/appengine-web.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
+  <runtime>java8</runtime>
   <service>tools</service>
-  <app-engine-apis>true</app-engine-apis>
+  <!--app-engine-apis>true</app-engine-apis-->
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <basic-scaling>
diff --git a/core/src/main/java/google/registry/env/sandbox/backend/WEB-INF/appengine-web.xml b/core/src/main/java/google/registry/env/sandbox/backend/WEB-INF/appengine-web.xml
index fd3f247541..cec30d9dc8 100644
--- a/core/src/main/java/google/registry/env/sandbox/backend/WEB-INF/appengine-web.xml
+++ b/core/src/main/java/google/registry/env/sandbox/backend/WEB-INF/appengine-web.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
+  <runtime>java8</runtime>
   <service>backend</service>
-  <app-engine-apis>true</app-engine-apis>
+  <!--app-engine-apis>true</app-engine-apis-->
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>
diff --git a/core/src/main/java/google/registry/env/sandbox/default/WEB-INF/appengine-web.xml b/core/src/main/java/google/registry/env/sandbox/default/WEB-INF/appengine-web.xml
index e03fd12afc..e8e6190477 100644
--- a/core/src/main/java/google/registry/env/sandbox/default/WEB-INF/appengine-web.xml
+++ b/core/src/main/java/google/registry/env/sandbox/default/WEB-INF/appengine-web.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
+  <runtime>java8</runtime>
   <service>default</service>
-  <app-engine-apis>true</app-engine-apis>
+  <!--app-engine-apis>true</app-engine-apis-->
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <manual-scaling>
diff --git a/core/src/main/java/google/registry/env/sandbox/pubapi/WEB-INF/appengine-web.xml b/core/src/main/java/google/registry/env/sandbox/pubapi/WEB-INF/appengine-web.xml
index 1268352234..8e5dfba6ec 100644
--- a/core/src/main/java/google/registry/env/sandbox/pubapi/WEB-INF/appengine-web.xml
+++ b/core/src/main/java/google/registry/env/sandbox/pubapi/WEB-INF/appengine-web.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
+  <runtime>java8</runtime>
   <service>pubapi</service>
-  <app-engine-apis>true</app-engine-apis>
+  <!--app-engine-apis>true</app-engine-apis-->
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <manual-scaling>
diff --git a/core/src/main/java/google/registry/env/sandbox/tools/WEB-INF/appengine-web.xml b/core/src/main/java/google/registry/env/sandbox/tools/WEB-INF/appengine-web.xml
index 8262a7ac8f..8a370de216 100644
--- a/core/src/main/java/google/registry/env/sandbox/tools/WEB-INF/appengine-web.xml
+++ b/core/src/main/java/google/registry/env/sandbox/tools/WEB-INF/appengine-web.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
+  <runtime>java8</runtime>
   <service>tools</service>
-  <app-engine-apis>true</app-engine-apis>
+  <!--app-engine-apis>true</app-engine-apis-->
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>