diff --git a/app/Api/V1/Controllers/AboutController.php b/app/Api/V1/Controllers/AboutController.php
index d9b0c174f1..721ec068fe 100644
--- a/app/Api/V1/Controllers/AboutController.php
+++ b/app/Api/V1/Controllers/AboutController.php
@@ -53,7 +53,7 @@ class AboutController extends Controller
         $search        = ['~', '#'];
         $replace       = ['\~', '# '];
         $phpVersion    = str_replace($search, $replace, PHP_VERSION);
-        $phpOs         = str_replace($search, $replace, php_uname());
+        $phpOs         = str_replace($search, $replace, PHP_OS);
         $currentDriver = DB::getDriverName();
         $data
                        = [
diff --git a/app/Api/V1/Controllers/Controller.php b/app/Api/V1/Controllers/Controller.php
index 3b79b6a678..68f0d0c91d 100644
--- a/app/Api/V1/Controllers/Controller.php
+++ b/app/Api/V1/Controllers/Controller.php
@@ -30,6 +30,7 @@ use Illuminate\Foundation\Auth\Access\AuthorizesRequests;
 use Illuminate\Foundation\Bus\DispatchesJobs;
 use Illuminate\Foundation\Validation\ValidatesRequests;
 use Illuminate\Routing\Controller as BaseController;
+use Log;
 use Symfony\Component\HttpFoundation\ParameterBag;
 
 /**
@@ -111,6 +112,7 @@ class Controller extends BaseController
                     $obj = new Carbon($date);
                 } catch (InvalidDateException $e) {
                     // don't care
+                    Log::error(sprintf('Invalid date exception in API controller: %s', $e->getMessage()));
                 }
             }
             $bag->set($field, $obj);
diff --git a/app/Api/V1/Controllers/UserController.php b/app/Api/V1/Controllers/UserController.php
index ddc30c04d3..4af7e7b7d8 100644
--- a/app/Api/V1/Controllers/UserController.php
+++ b/app/Api/V1/Controllers/UserController.php
@@ -70,6 +70,7 @@ class UserController extends Controller
      * @param  \FireflyIII\User $user
      *
      * @return \Illuminate\Http\Response
+     * @throws \Symfony\Component\HttpFoundation\File\Exception\AccessDeniedException
      */
     public function delete(User $user)
     {
diff --git a/app/Api/V1/Requests/AccountRequest.php b/app/Api/V1/Requests/AccountRequest.php
index e115c07dc9..44977d41e2 100644
--- a/app/Api/V1/Requests/AccountRequest.php
+++ b/app/Api/V1/Requests/AccountRequest.php
@@ -70,9 +70,9 @@ class AccountRequest extends Request
      */
     public function rules(): array
     {
-        $accountRoles   = join(',', config('firefly.accountRoles'));
-        $types          = join(',', array_keys(config('firefly.subTitlesByIdentifier')));
-        $ccPaymentTypes = join(',', array_keys(config('firefly.ccTypes')));
+        $accountRoles   = implode(',', config('firefly.accountRoles'));
+        $types          = implode(',', array_keys(config('firefly.subTitlesByIdentifier')));
+        $ccPaymentTypes = implode(',', array_keys(config('firefly.ccTypes')));
         $rules          = [
             'name'                    => 'required|min:1|uniqueAccountForUser',
             'opening_balance'         => 'numeric|required_with:opening_balance_date|nullable',
diff --git a/app/Api/V1/Requests/TransactionRequest.php b/app/Api/V1/Requests/TransactionRequest.php
index efef5a3658..9d94981a85 100644
--- a/app/Api/V1/Requests/TransactionRequest.php
+++ b/app/Api/V1/Requests/TransactionRequest.php
@@ -168,6 +168,7 @@ class TransactionRequest extends Request
      * @param  Validator $validator
      *
      * @return void
+     * @throws \FireflyIII\Exceptions\FireflyException
      */
     public function withValidator(Validator $validator): void
     {
@@ -438,10 +439,8 @@ class TransactionRequest extends Request
 
             }
             // add some errors in case of same account submitted:
-            if (!is_null($sourceAccount) && !is_null($destinationAccount)) {
-                if ($sourceAccount->id === $destinationAccount->id) {
-                    $validator->errors()->add($idField, trans('validation.source_equals_destination'));
-                }
+            if (!is_null($sourceAccount) && !is_null($destinationAccount) && $sourceAccount->id === $destinationAccount->id) {
+                $validator->errors()->add($idField, trans('validation.source_equals_destination'));
             }
         }
     }
@@ -506,8 +505,6 @@ class TransactionRequest extends Request
                 );
             // @codeCoverageIgnoreEnd
         }
-
-        return;
     }
 
 }
diff --git a/app/Http/Controllers/Transaction/BulkController.php b/app/Http/Controllers/Transaction/BulkController.php
index 4ed21079dc..3c98c177a3 100644
--- a/app/Http/Controllers/Transaction/BulkController.php
+++ b/app/Http/Controllers/Transaction/BulkController.php
@@ -70,6 +70,7 @@ class BulkController extends Controller
      * @param Collection $journals
      *
      * @return View
+     * @throws \RuntimeException
      */
     public function edit(Request $request, Collection $journals)
     {
@@ -139,6 +140,7 @@ class BulkController extends Controller
      * @param JournalRepositoryInterface $repository
      *
      * @return mixed
+     * @throws \RuntimeException
      */
     public function update(BulkEditJournalRequest $request, JournalRepositoryInterface $repository)
     {
diff --git a/app/Http/Controllers/Transaction/LinkController.php b/app/Http/Controllers/Transaction/LinkController.php
index 5bd8c3ae20..86d6618e18 100644
--- a/app/Http/Controllers/Transaction/LinkController.php
+++ b/app/Http/Controllers/Transaction/LinkController.php
@@ -110,6 +110,13 @@ class LinkController extends Controller
         }
         $other         = $this->journalRepository->find($linkInfo['transaction_journal_id']);
         $alreadyLinked = $this->repository->findLink($journal, $other);
+
+        if($other->id === $journal->id) {
+            Session::flash('error', trans('firefly.journals_link_to_self'));
+
+            return redirect(route('transactions.show', [$journal->id]));
+        }
+
         if ($alreadyLinked) {
             Session::flash('error', trans('firefly.journals_error_linked'));
 
diff --git a/app/Http/Controllers/Transaction/SingleController.php b/app/Http/Controllers/Transaction/SingleController.php
index 287da2d212..b9dcc296a6 100644
--- a/app/Http/Controllers/Transaction/SingleController.php
+++ b/app/Http/Controllers/Transaction/SingleController.php
@@ -102,7 +102,7 @@ class SingleController extends Controller
         $budgetId     = $this->repository->getJournalBudgetId($journal);
         $categoryName = $this->repository->getJournalCategoryName($journal);
 
-        $tags = join(',', $this->repository->getTags($journal));
+        $tags = implode(',', $this->repository->getTags($journal));
         /** @var Transaction $transaction */
         $transaction   = $journal->transactions()->first();
         $amount        = app('steam')->positive($transaction->amount);
@@ -280,7 +280,7 @@ class SingleController extends Controller
             'process_date'             => $repository->getJournalDate($journal, 'process_date'),
             'category'                 => $repository->getJournalCategoryName($journal),
             'budget_id'                => $repository->getJournalBudgetId($journal),
-            'tags'                     => join(',', $repository->getTags($journal)),
+            'tags'                     => implode(',', $repository->getTags($journal)),
             'source_account_id'        => $sourceAccounts->first()->id,
             'source_account_name'      => $sourceAccounts->first()->edit_name,
             'destination_account_id'   => $destinationAccounts->first()->id,
@@ -441,10 +441,6 @@ class SingleController extends Controller
     {
         $count = $this->repository->countTransactions($journal);
 
-        if ($count > 2) {
-            return true; // @codeCoverageIgnore
-        }
-
-        return false;
+        return $count > 2;
     }
 }
diff --git a/app/Http/Controllers/Transaction/SplitController.php b/app/Http/Controllers/Transaction/SplitController.php
index a22d913b1d..be620809ce 100644
--- a/app/Http/Controllers/Transaction/SplitController.php
+++ b/app/Http/Controllers/Transaction/SplitController.php
@@ -125,7 +125,7 @@ class SplitController extends Controller
 
         return view(
             'transactions.split.edit', compact(
-                                         'subTitleIcon', 'currencies', 'optionalFields', 'preFilled', 'subTitle', 'uploadSize', 'assetAccounts', 'budgets',
+                                         'subTitleIcon', 'currencies', 'optionalFields', 'preFilled', 'subTitle', 'uploadSize', 'budgets',
                                          'journal', 'accountArray',
                                          'previous'
                                      )
@@ -197,7 +197,7 @@ class SplitController extends Controller
             'destinationAccounts'            => $destinationAccounts,
             'what'                           => strtolower($this->repository->getTransactionType($journal)),
             'date'                           => $request->old('date', $this->repository->getJournalDate($journal, null)),
-            'tags'                           => join(',', $journal->tags->pluck('tag')->toArray()),
+            'tags'                           => implode(',', $journal->tags->pluck('tag')->toArray()),
 
             // all custom fields:
             'interest_date'                  => $request->old('interest_date', $this->repository->getMetaField($journal, 'interest_date')),
diff --git a/app/User.php b/app/User.php
index d01ef2daae..2d7f793027 100644
--- a/app/User.php
+++ b/app/User.php
@@ -76,6 +76,7 @@ class User extends Authenticatable
      * @param string $value
      *
      * @return User
+     * @throws \Symfony\Component\HttpKernel\Exception\NotFoundHttpException
      */
     public static function routeBinder(string $value): User
     {
diff --git a/resources/lang/en_US/firefly.php b/resources/lang/en_US/firefly.php
index a6a61fb5d1..5080e9f348 100644
--- a/resources/lang/en_US/firefly.php
+++ b/resources/lang/en_US/firefly.php
@@ -1086,6 +1086,7 @@ return [
     'invalid_link_selection'                => 'Cannot link these transactions',
     'journals_linked'                       => 'Transactions are linked.',
     'journals_error_linked'                 => 'These transactions are already linked.',
+    'journals_link_to_self'                 => 'You cannot link a transaction to itself',
     'journal_links'                         => 'Transaction links',
     'this_withdrawal'                       => 'This withdrawal',
     'this_deposit'                          => 'This deposit',