diff --git a/frontend/app/utils/errorUtils.ts b/frontend/app/utils/errorUtils.ts
index 3e0db38d15..62ed3e0ccb 100644
--- a/frontend/app/utils/errorUtils.ts
+++ b/frontend/app/utils/errorUtils.ts
@@ -23,68 +23,72 @@ export const errorMessages = defineMessages<string | number>({
   },
   4: {
     id: 'errors.4',
-    defaultMessage: `Invalid comment data.`,
+    defaultMessage: 'Invalid comment data.',
   },
   5: {
     id: 'errors.5',
-    defaultMessage: `Comment cannot be found. Please refresh the page and try again.`,
+    defaultMessage: 'Comment cannot be found. Please refresh the page and try again.',
   },
   6: {
     id: 'errors.6',
-    defaultMessage: `Site cannot be found. Please refresh the page and try again.`,
+    defaultMessage: 'Site cannot be found. Please refresh the page and try again.',
   },
   7: {
     id: 'errors.7',
-    defaultMessage: `User has been blocked.`,
+    defaultMessage: 'User has been blocked.',
   },
   8: {
     id: 'errors.8',
-    defaultMessage: `User has been blocked.`,
+    defaultMessage: `Can't post comments on this page. Comments are read only.`,
   },
   9: {
     id: 'errors.9',
-    defaultMessage: `Comment changing failed. Please try again a bit later.`,
+    defaultMessage: 'Comment changing failed. Please try again a bit later.',
   },
   10: {
     id: 'errors.10',
-    defaultMessage: `It is too late to edit the comment.`,
+    defaultMessage: 'It is too late to edit the comment.',
   },
   11: {
     id: 'errors.11',
-    defaultMessage: `Comment already has reply, editing is not possible.`,
+    defaultMessage: 'Comment already has reply, editing is not possible.',
   },
   12: {
     id: 'errors.12',
-    defaultMessage: `Cannot save voting result. Please try again a bit later.`,
+    defaultMessage: 'Cannot save voting result. Please try again a bit later.',
   },
   13: {
     id: 'errors.13',
-    defaultMessage: `You cannot vote for your own comment.`,
+    defaultMessage: 'You cannot vote for your own comment.',
   },
   14: {
     id: 'errors.14',
-    defaultMessage: `You have already voted for the comment.`,
+    defaultMessage: 'You have already voted for the comment.',
   },
   15: {
     id: 'errors.15',
-    defaultMessage: `Too many votes for the comment.`,
+    defaultMessage: 'Too many votes for the comment.',
   },
   16: {
     id: 'errors.16',
-    defaultMessage: `Min score reached for the comment.`,
+    defaultMessage: 'Min score reached for the comment.',
   },
   17: {
     id: 'errors.17',
-    defaultMessage: `Action rejected. Please try again a bit later.`,
+    defaultMessage: 'Action rejected. Please try again a bit later.',
   },
   18: {
     id: 'errors.18',
-    defaultMessage: `Requested file cannot be found.`,
+    defaultMessage: 'Requested file cannot be found.',
   },
   19: {
     id: 'errors.19',
     defaultMessage: 'Comment contains restricted words.',
   },
+  20: {
+    id: 'errors.20',
+    defaultMessage: 'Posted image not found. Please try to upload it again.',
+  },
   401: {
     id: 'errors.not-authorized',
     defaultMessage: 'Not authorized.',