diff --git a/mod/salmon.php b/mod/salmon.php
index ea5c334c08..bc4410434b 100644
--- a/mod/salmon.php
+++ b/mod/salmon.php
@@ -79,7 +79,7 @@ function salmon_post(App $a, $xml = '') {
 	// stash away some other stuff for later
 
 	$type = $base->data[0]->attributes()->type[0];
-	$keyhash = $base->sig[0]->attributes()->keyhash[0];
+	$keyhash = $base->sig[0]->attributes()->keyhash[0] ?? '';
 	$encoding = $base->encoding;
 	$alg = $base->alg;
 
diff --git a/src/Content/Nav.php b/src/Content/Nav.php
index 4a9c71ce9f..335f81bf3d 100644
--- a/src/Content/Nav.php
+++ b/src/Content/Nav.php
@@ -187,7 +187,7 @@ class Nav
 					'name' => $a->user['username'],
 				];
 			} else {
-				DI::logger()->warning('Empty $a->user for local user'. ['local_user' => local_user(), '$a' => $a]);
+				DI::logger()->warning('Empty $a->user for local user', ['local_user' => local_user(), '$a' => $a]);
 			}
 		}
 
@@ -256,7 +256,7 @@ class Nav
 		}
 
 		// The following nav links are only show to logged in users
-		if (local_user()) {
+		if (local_user() && !empty($a->user)) {
 			$nav['network'] = ['network', DI::l10n()->t('Network'), '', DI::l10n()->t('Conversations from your friends')];
 
 			$nav['home'] = ['profile/' . $a->user['nickname'], DI::l10n()->t('Home'), '', DI::l10n()->t('Your posts and conversations')];
diff --git a/src/Model/Contact.php b/src/Model/Contact.php
index b11919b528..46104aaeae 100644
--- a/src/Model/Contact.php
+++ b/src/Model/Contact.php
@@ -1077,7 +1077,6 @@ class Contact
 		}
 
 		if (DBA::isResult($r)) {
-			$authoritativeResult = true;
 			// If there is more than one entry we filter out the connector networks
 			if (count($r) > 1) {
 				foreach ($r as $id => $result) {
@@ -1088,7 +1087,10 @@ class Contact
 			}
 
 			$profile = array_shift($r);
+		}
 
+		if (!empty($profile)) {
+			$authoritativeResult = true;
 			// "bd" always contains the upcoming birthday of a contact.
 			// "birthday" might contain the birthday including the year of birth.
 			if ($profile["birthday"] > DBA::NULL_DATE) {
diff --git a/src/Module/Diaspora/Fetch.php b/src/Module/Diaspora/Fetch.php
index aba9d33be7..c94badf7e3 100644
--- a/src/Module/Diaspora/Fetch.php
+++ b/src/Module/Diaspora/Fetch.php
@@ -59,7 +59,7 @@ class Fetch extends BaseModule
 		if (empty($item)) {
 			$condition = ['guid' => $guid, 'network' => [Protocol::DFRN, Protocol::DIASPORA]];
 			$item = Item::selectFirst(['author-link'], $condition);
-			if (empty($item)) {
+			if (!empty($item["author-link"])) {
 				$parts = parse_url($item["author-link"]);
 				if (empty($parts["scheme"]) || empty($parts["host"])) {
 					throw new HTTPException\InternalServerErrorException();
diff --git a/src/Module/Search/Acl.php b/src/Module/Search/Acl.php
index 82880f83c3..cc8df3eab2 100644
--- a/src/Module/Search/Acl.php
+++ b/src/Module/Search/Acl.php
@@ -79,6 +79,11 @@ class Acl extends BaseModule
 
 		$contacts = [];
 		foreach ($r as $g) {
+			if (empty($g['name'])) {
+				DI::logger()->warning('Wrong result item from Search::searchGlobalContact', ['$g' => $g, '$search' => $search, '$mode' => $mode, '$page' => $page]);
+				continue;
+			}
+
 			$contacts[] = [
 				'photo'   => ProxyUtils::proxifyUrl($g['photo'], false, ProxyUtils::SIZE_MICRO),
 				'name'    => htmlspecialchars($g['name']),