Make sure IBAN's have their spaces removed.

app/Console/Commands/Correction/CorrectDatabase.php

@@ -69,6 +69,7 @@ class CorrectDatabase extends Command
             'firefly-iii:delete-empty-journals',
             'firefly-iii:delete-empty-groups',
             'firefly-iii:fix-account-types',
+            'firefly-iii:fix-ibans',
             'firefly-iii:fix-account-order',
             'firefly-iii:rename-meta-fields',
             'firefly-iii:fix-ob-currencies',

app/Console/Commands/Correction/FixIbans.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace FireflyIII\Console\Commands\Correction;
+
+use FireflyIII\Models\Account;
+use Illuminate\Console\Command;
+
+/**
+ * Class FixIbans
+ */
+class FixIbans extends Command
+{
+    /**
+     * The console command description.
+     *
+     * @var string
+     */
+    protected $description = 'Removes spaces from IBANs';
+    /**
+     * The name and signature of the console command.
+     *
+     * @var string
+     */
+    protected $signature = 'firefly-iii:fix-ibans';
+
+    /**
+     * Execute the console command.
+     *
+     * @return int
+     */
+    public function handle(): int
+    {
+        $accounts = Account::whereNotNull('iban')->get();
+        /** @var Account $account */
+        foreach ($accounts as $account) {
+            $iban = $account->iban;
+            if (str_contains($iban, ' ')) {
+
+                $iban = app('steam')->filterSpaces((string)$account->iban);
+                if ('' !== $iban) {
+                    $account->iban = $iban;
+                    $account->save();
+                    $this->line(sprintf('Removed spaces from IBAN of account #%d', $account->id));
+                }
+            }
+        }
+
+        return 0;
+    }
+}

app/Console/Commands/Upgrade/UpgradeDatabase.php

@@ -98,6 +98,7 @@ class UpgradeDatabase extends Command
             'firefly-iii:unify-group-accounts',
             'firefly-iii:fix-transaction-types',
             'firefly-iii:fix-frontpage-accounts',
+            'firefly-iii:fix-ibans',
 
             // two report commands
             'firefly-iii:report-empty-objects',

app/Http/Controllers/System/InstallController.php

@@ -109,6 +109,7 @@ class InstallController extends Controller
             'firefly-iii:unify-group-accounts'         => [],
             'firefly-iii:fix-transaction-types'        => [],
             'firefly-iii:fix-frontpage-accounts'       => [],
+            'firefly-iii:fix-ibans'                    => [],
 
             // final command to set latest version in DB
             'firefly-iii:set-latest-version'           => ['--james-is-cool' => true],

app/Services/Internal/Support/AccountServiceTrait.php

@@ -69,7 +69,8 @@ trait AccountServiceTrait
             return null;
         }
 
-        return $iban;
+
+        return app('steam')->filterSpaces($iban);
     }
 
     /**

app/Services/Internal/Update/AccountUpdateService.php

@@ -135,7 +135,7 @@ class AccountUpdateService
             $account->active = $data['active'];
         }
         if (array_key_exists('iban', $data)) {
-            $account->iban = $data['iban'];
+            $account->iban = app('steam')->filterSpaces((string)$data['iban']);
         }
 
         // set liability, but account must already be a liability.

app/Support/Steam.php

@@ -540,4 +540,62 @@ class Steam
         return $amount;
     }
 
+    /**
+     * @param string $string
+     *
+     * @return string
+     */
+    public function filterSpaces(string $string): string
+    {
+        $search = [
+            "\u{0001}", // start of heading
+            "\u{0002}", // start of text
+            "\u{0003}", // end of text
+            "\u{0004}", // end of transmission
+            "\u{0005}", // enquiry
+            "\u{0006}", // ACK
+            "\u{0007}", // BEL
+            "\u{0008}", // backspace
+            "\u{000E}", // shift out
+            "\u{000F}", // shift in
+            "\u{0010}", // data link escape
+            "\u{0011}", // DC1
+            "\u{0012}", // DC2
+            "\u{0013}", // DC3
+            "\u{0014}", // DC4
+            "\u{0015}", // NAK
+            "\u{0016}", // SYN
+            "\u{0017}", // ETB
+            "\u{0018}", // CAN
+            "\u{0019}", // EM
+            "\u{001A}", // SUB
+            "\u{001B}", // escape
+            "\u{001C}", // file separator
+            "\u{001D}", // group separator
+            "\u{001E}", // record separator
+            "\u{001F}", // unit separator
+            "\u{007F}", // DEL
+            "\u{00A0}", // non-breaking space
+            "\u{1680}", // ogham space mark
+            "\u{180E}", // mongolian vowel separator
+            "\u{2000}", // en quad
+            "\u{2001}", // em quad
+            "\u{2002}", // en space
+            "\u{2003}", // em space
+            "\u{2004}", // three-per-em space
+            "\u{2005}", // four-per-em space
+            "\u{2006}", // six-per-em space
+            "\u{2007}", // figure space
+            "\u{2008}", // punctuation space
+            "\u{2009}", // thin space
+            "\u{200A}", // hair space
+            "\u{200B}", // zero width space
+            "\u{202F}", // narrow no-break space
+            "\u{3000}", // ideographic space
+            "\u{FEFF}", // zero width no -break space
+            "\x20", // plain old normal space
+        ];
+
+        return str_replace($search, '', $string);
+    }
 }