diff --git a/Dockerfile b/Dockerfile
index ae8b103d3..be3b962df 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -17,7 +17,6 @@ FROM eclipse-temurin:17-jdk-alpine
 # TODO remove the fix once a new version is released
 RUN apk update && apk upgrade --no-cache libcrypto3 libssl3
 
-ENV JAVA_OPTS="-Dgflog.config=/app/config/gflog.xml"
 ENV OTEL_TRACES_EXPORTER="none"
 ENV OTEL_METRICS_EXPORTER="none"
 ENV OTEL_LOGS_EXPORTER="none"
@@ -27,7 +26,6 @@ WORKDIR /app
 RUN adduser -u 1001 --disabled-password --gecos "" appuser
 
 COPY --from=builder --chown=appuser:appuser /build/ .
-COPY --chown=appuser:appuser ./config/* /app/config/
 RUN mkdir /app/log && chown -R appuser:appuser /app
 
 USER appuser
diff --git a/README.md b/README.md
index de55c6aa9..1a03fa7a0 100644
--- a/README.md
+++ b/README.md
@@ -59,7 +59,6 @@ Static settings are used on startup and cannot be changed while application is r
 | storage.createBucket                       | false              | Indicates whether bucket should be created on start-up                                                            
 | encryption.password                        | -                  | Password used for AES encryption                                                                                  
 | encryption.salt                            | -                  | Salt used for AES encryption                                                                                      
-| encryption.salt                            | -                  | Salt used for AES encryption                                                                                      
 | resources.maxSize                          | 1048576            | Max allowed size in bytes for a resource
 | resources.syncPeriod                       | 60000              | Period in milliseconds, how frequently check for resources to sync
 | resources.syncDelay                        | 120000             | Delay in milliseconds for a resource to be written back in object storage after last modification
@@ -76,7 +75,7 @@ maxmemory 4G
 maxmemory-policy volatile-lfu
 ```
 
-Note: Redis will be strictly required in the upcoming releases 0.7+.
+Note: Redis will be strictly required in the upcoming releases 0.8+.
 
 ### Dynamic settings
 
diff --git a/config/gflog.xml b/config/gflog.xml
deleted file mode 100644
index 4f11fdef1..000000000
--- a/config/gflog.xml
+++ /dev/null
@@ -1,17 +0,0 @@
-<config>
-    <appender name="console" factory="com.epam.deltix.gflog.core.appender.ConsoleAppenderFactory"/>
-    <appender name="file" factory="com.epam.deltix.gflog.core.appender.DailyRollingFileAppenderFactory"
-              bufferCapacity="32m" file="/app/log/aidial.log" maxFiles="10" maxFileSize="1g">
-        <layout template="%m%n"/>
-    </appender>
-
-    <logger level="INFO">
-        <appender-ref ref="console"/>
-    </logger>
-
-    <logger level="INFO" name="aidial.log">
-        <appender-ref ref="file"/>
-    </logger>
-
-    <service entryEncoding="UTF-8" entryMaxCapacity="30m" bufferCapacity="128m"/>
-</config>
\ No newline at end of file
diff --git a/src/main/java/com/epam/aidial/core/config/FileConfigStore.java b/src/main/java/com/epam/aidial/core/config/FileConfigStore.java
index a71ebfb41..a685d2e97 100644
--- a/src/main/java/com/epam/aidial/core/config/FileConfigStore.java
+++ b/src/main/java/com/epam/aidial/core/config/FileConfigStore.java
@@ -108,15 +108,11 @@ private void load(boolean fail) {
     }
 
     private Config loadConfig() throws Exception {
-        JsonNode tree = null;
+        JsonNode tree = ProxyUtil.MAPPER.createObjectNode();
 
         for (String path : paths) {
             try (InputStream stream = openStream(path)) {
-                if (tree == null) {
-                    tree = ProxyUtil.MAPPER.readTree(stream);
-                } else {
-                    tree = ProxyUtil.MAPPER.readerForUpdating(tree).readTree(stream);
-                }
+                tree = ProxyUtil.MAPPER.readerForUpdating(tree).readTree(stream);
             }
         }
 
diff --git a/src/main/java/com/epam/aidial/core/controller/ResourceController.java b/src/main/java/com/epam/aidial/core/controller/ResourceController.java
index 71818ee1f..b49ee99dd 100644
--- a/src/main/java/com/epam/aidial/core/controller/ResourceController.java
+++ b/src/main/java/com/epam/aidial/core/controller/ResourceController.java
@@ -9,6 +9,7 @@
 import com.epam.aidial.core.util.ProxyUtil;
 import io.vertx.core.Future;
 import io.vertx.core.Vertx;
+import io.vertx.core.http.HttpHeaders;
 import io.vertx.core.http.HttpMethod;
 import lombok.extern.slf4j.Slf4j;
 
@@ -106,6 +107,13 @@ private Future<?> putResource(ResourceDescription descriptor) {
             return context.respond(HttpStatus.REQUEST_ENTITY_TOO_LARGE, message);
         }
 
+        String ifNoneMatch = context.getRequest().getHeader(HttpHeaders.IF_NONE_MATCH);
+        boolean overwrite = (ifNoneMatch == null);
+
+        if (ifNoneMatch != null && !ifNoneMatch.equals("*")) {
+            return context.respond(HttpStatus.BAD_REQUEST, "only header if-none-match=* is supported");
+        }
+
         return context.getRequest().body().compose(bytes -> {
                     if (bytes.length() > contentLimit) {
                         String message = "Resource size: %s exceeds max limit: %s".formatted(bytes.length(), contentLimit);
@@ -113,9 +121,15 @@ private Future<?> putResource(ResourceDescription descriptor) {
                     }
 
                     String body = bytes.toString(StandardCharsets.UTF_8);
-                    return vertx.executeBlocking(() -> service.putResource(descriptor, body));
+                    return vertx.executeBlocking(() -> service.putResource(descriptor, body, overwrite));
+                })
+                .onSuccess((metadata) -> {
+                    if (metadata == null) {
+                        context.respond(HttpStatus.CONFLICT, "Resource already exists: " + descriptor.getUrl());
+                    } else {
+                        context.respond(HttpStatus.OK, metadata);
+                    }
                 })
-                .onSuccess((metadata) -> context.respond(HttpStatus.OK, metadata))
                 .onFailure(error -> {
                     if (error instanceof HttpException exception) {
                         context.respond(exception.getStatus(), exception.getMessage());
diff --git a/src/main/java/com/epam/aidial/core/service/ResourceService.java b/src/main/java/com/epam/aidial/core/service/ResourceService.java
index 0cd8256eb..6361112c3 100644
--- a/src/main/java/com/epam/aidial/core/service/ResourceService.java
+++ b/src/main/java/com/epam/aidial/core/service/ResourceService.java
@@ -67,11 +67,11 @@ public ResourceService(Vertx vertx,
     }
 
     /**
-     * @param maxSize - max allowed size in bytes for a resource.
-     * @param syncPeriod - period in milliseconds, how frequently check for resources to sync.
-     * @param syncDelay - delay in milliseconds for a resource to be written back in object storage after last modification.
-     * @param syncBatch - how many resources to sync in one go.
-     * @param cacheExpiration - expiration in milliseconds for synced resources in Redis.
+     * @param maxSize            - max allowed size in bytes for a resource.
+     * @param syncPeriod         - period in milliseconds, how frequently check for resources to sync.
+     * @param syncDelay          - delay in milliseconds for a resource to be written back in object storage after last modification.
+     * @param syncBatch          - how many resources to sync in one go.
+     * @param cacheExpiration    - expiration in milliseconds for synced resources in Redis.
      * @param compressionMinSize - compress resources with gzip if their size in bytes more or equal to this value.
      */
     public ResourceService(Vertx vertx,
@@ -192,11 +192,12 @@ public String getResource(ResourceDescription descriptor, boolean lock) {
         return result.exists ? result.body : null;
     }
 
-    public ResourceItemMetadata putResource(ResourceDescription descriptor, String body) {
-        return putResource(descriptor, body, true);
+    public ResourceItemMetadata putResource(ResourceDescription descriptor, String body, boolean overwrite) {
+        return putResource(descriptor, body, overwrite, true);
     }
 
-    public ResourceItemMetadata putResource(ResourceDescription descriptor, String body, boolean lock) {
+    public ResourceItemMetadata putResource(ResourceDescription descriptor, String body,
+                                            boolean overwrite, boolean lock) {
         String redisKey = redisKey(descriptor);
         String blobKey = blobKey(descriptor);
 
@@ -206,6 +207,10 @@ public ResourceItemMetadata putResource(ResourceDescription descriptor, String b
                 result = blobGet(blobKey, false);
             }
 
+            if (result.exists && !overwrite) {
+                return null;
+            }
+
             long updatedAt = time();
             long createdAt = result.exists ? result.createdAt : updatedAt;
             redisPut(redisKey, new Result(body, createdAt, updatedAt, false, true));
@@ -224,7 +229,7 @@ public void computeResource(ResourceDescription descriptor, Function<String, Str
         try (var ignore = lockService.lock(redisKey)) {
             String body = getResource(descriptor, false);
             String updatedBody = fn.apply(body);
-            putResource(descriptor, updatedBody, false);
+            putResource(descriptor, updatedBody, true, false);
         }
     }
 
diff --git a/src/main/java/com/epam/aidial/core/util/HttpStatus.java b/src/main/java/com/epam/aidial/core/util/HttpStatus.java
index 1b66c9764..759de6860 100644
--- a/src/main/java/com/epam/aidial/core/util/HttpStatus.java
+++ b/src/main/java/com/epam/aidial/core/util/HttpStatus.java
@@ -13,6 +13,7 @@ public enum HttpStatus {
     FORBIDDEN(403),
     NOT_FOUND(404),
     METHOD_NOT_ALLOWED(405),
+    CONFLICT(409),
     REQUEST_ENTITY_TOO_LARGE(413),
     UNSUPPORTED_MEDIA_TYPE(415),
     UNPROCESSABLE_ENTITY(422),
diff --git a/src/test/java/com/epam/aidial/core/ResourceApiTest.java b/src/test/java/com/epam/aidial/core/ResourceApiTest.java
index 1f5ef5daf..00ee31406 100644
--- a/src/test/java/com/epam/aidial/core/ResourceApiTest.java
+++ b/src/test/java/com/epam/aidial/core/ResourceApiTest.java
@@ -131,6 +131,9 @@ void testWorkflow() {
         response = request(HttpMethod.PUT, "/folder/conversation", "12345");
         verifyNotExact(response, 200, "\"url\":\"conversations/3CcedGxCx23EwiVbVmscVktScRyf46KypuBQ65miviST/folder/conversation\"");
 
+        response = request(HttpMethod.PUT, "/folder/conversation", "12345", "if-none-match", "*");
+        verifyNotExact(response, 409, "Resource already exists: conversations/3CcedGxCx23EwiVbVmscVktScRyf46KypuBQ65miviST/folder/conversation");
+
         response = request(HttpMethod.GET, "/folder/conversation");
         verify(response, 200, "12345");
 
@@ -165,6 +168,12 @@ void testLimit() {
         verify(response, 413, "Resource size: 1048577 exceeds max limit: 1048576");
     }
 
+    @Test
+    void testUnsupportedIfNoneMatchHeader() {
+        Response response = request(HttpMethod.PUT, "/folder/big", "1", "if-none-match", "unsupported");
+        verify(response, 400, "only header if-none-match=* is supported");
+    }
+
     @Test
     void testRandom() {
         ThreadLocalRandom random = ThreadLocalRandom.current();
@@ -226,8 +235,8 @@ private Response request(HttpMethod method, String resource) {
         return request(method, resource, "");
     }
 
-    private Response request(HttpMethod method, String resource, String body) {
-        return send(method, "/v1/conversations/" + bucket + resource, body);
+    private Response request(HttpMethod method, String resource, String body, String... headers) {
+        return send(method, "/v1/conversations/" + bucket + resource, body, headers);
     }
 
     private Response metadata(String resource) {
@@ -235,7 +244,7 @@ private Response metadata(String resource) {
     }
 
     @SneakyThrows
-    private Response send(HttpMethod method, String path, String body) {
+    private Response send(HttpMethod method, String path, String body, String... headers) {
         String uri = "http://127.0.0.1:" + dial.getServer().actualPort() + path;
         HttpUriRequest request;
 
@@ -253,6 +262,12 @@ private Response send(HttpMethod method, String path, String body) {
 
         request.addHeader("api-key", "proxyKey1");
 
+        for (int i = 0; i < headers.length; i += 2) {
+            String key = headers[i];
+            String value = headers[i + 1];
+            request.addHeader(key, value);
+        }
+
         try (CloseableHttpResponse response = client.execute(request)) {
             int status = response.getStatusLine().getStatusCode();
             String answer = EntityUtils.toString(response.getEntity());