diff --git a/doc/configuration.txt b/doc/configuration.txt
index e65b073..9307437 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -4384,9 +4384,12 @@
   If the keyword "id" is used instead of "len", the action tries to store the
   captured string in a previously declared capture slot. This is useful to run
   captures in backends. The slot id can be declared by a previous directive
-  "http-request capture" or with the "declare capture" keyword. If the slot
-  <id> doesn't exist, then HAProxy fails parsing the configuration to prevent
-  unexpected behavior at run time.
+  "http-request capture" or with the "declare capture" keyword.
+
+  When using this action in a backend, double check that the relevant
+  frontend(s) have the required capture slots otherwise, this rule will be
+  ignored at run time. This can't be detected at configuration parsing time
+  due to HAProxy's ability to dynamically resolve backend name at runtime.
 
 http-request del-acl(<file-name>) <key fmt> [ { if | unless } <condition> ]
 
@@ -5048,8 +5051,11 @@
   This is useful to run captures in backends. The slot id can be declared by a
   previous directive "http-response capture" or with the "declare capture"
   keyword.
-  If the slot <id> doesn't exist, then HAProxy fails parsing the configuration
-  to prevent unexpected behavior at run time.
+
+  When using this action in a backend, double check that the relevant
+  frontend(s) have the required capture slots otherwise, this rule will be
+  ignored at run time. This can't be detected at configuration parsing time
+  due to HAProxy's ability to dynamically resolve backend name at runtime.
 
 http-response del-acl(<file-name>) <key fmt> [ { if | unless } <condition> ]
 
diff --git a/src/http_act.c b/src/http_act.c
index 0653dd5..cf3d12c 100644
--- a/src/http_act.c
+++ b/src/http_act.c
@@ -420,7 +420,10 @@
 	if (rule->action_ptr != http_action_req_capture_by_id)
 		return 1;
 
-	if (rule->arg.capid.idx >= px->nb_req_cap) {
+	/* capture slots can only be declared in frontends, so we can't check their
+	 * existence in backends at configuration parsing step
+	 */
+	if (px->cap & PR_CAP_FE && rule->arg.capid.idx >= px->nb_req_cap) {
 		memprintf(err, "unable to find capture id '%d' referenced by http-request capture rule",
 			  rule->arg.capid.idx);
 		return 0;