diff --git a/api-ref/source/v2/volumes-v2-volumes-actions.inc b/api-ref/source/v2/volumes-v2-volumes-actions.inc
index 691d4436bba..fb222f3b2e8 100644
--- a/api-ref/source/v2/volumes-v2-volumes-actions.inc
+++ b/api-ref/source/v2/volumes-v2-volumes-actions.inc
@@ -405,6 +405,11 @@ Policy defaults enable only users with the administrative role or the owner of
 the volume to perform this operation. Cloud providers can change these
 permissions through the policy configuration file.
 
+Retyping an unencrypted volume to the same size encrypted volume will most
+likely fail. Even though the volume is the same size as the source volume, the
+encrypted volume needs to store additional encryption information overhead.
+This results in the new volume not being large enough to hold all data.
+
 Response codes
 --------------
 
diff --git a/api-ref/source/v3/volumes-v3-volumes-actions.inc b/api-ref/source/v3/volumes-v3-volumes-actions.inc
index 009b1c05156..935a0f4c6c1 100644
--- a/api-ref/source/v3/volumes-v3-volumes-actions.inc
+++ b/api-ref/source/v3/volumes-v3-volumes-actions.inc
@@ -461,6 +461,11 @@ Policy defaults enable only users with the administrative role or the owner of
 the volume to perform this operation. Cloud providers can change these
 permissions through the policy configuration file.
 
+Retyping an unencrypted volume to the same size encrypted volume will most
+likely fail. Even though the volume is the same size as the source volume, the
+encrypted volume needs to store additional encryption information overhead.
+This results in the new volume not being large enough to hold all data.
+
 Response codes
 --------------
 
diff --git a/doc/source/configuration/block-storage/volume-encryption.rst b/doc/source/configuration/block-storage/volume-encryption.rst
index b46c5f9b560..f15940b5b74 100644
--- a/doc/source/configuration/block-storage/volume-encryption.rst
+++ b/doc/source/configuration/block-storage/volume-encryption.rst
@@ -218,3 +218,12 @@ sections.
 
 In the above example you see that the search returns the string
 written to the unencrypted volume, but not the encrypted one.
+
+Known Issues
+~~~~~~~~~~~~
+
+Retyping an unencrypted volume to the same size encrypted volume will
+most likely fail. Even though the volume is the same size as the source
+volume, the encrypted volume needs to store additional encryption
+information overhead. This results in the new volume not being large
+enough to hold all data.