Laravel : "mcrypt_decrypt(): The IV parameter must be as long as the blocksize"

Question

I ran composer update on a Laravel application, and now I am getting this error:

mcrypt_decrypt(): The IV parameter must be as long as the blocksize

What happened?!

cool [Ed Rands's comment][1] worked for me just to clean up the cookies [1]: http://stackoverflow.com/a/23922994/1539590 — JaydenLiu, Nov 21 '14 at 17:54

score 26 · Accepted Answer · edited Jun 05 '14 at 20:27

26

I figured this out. All you have to do is clear your cookies, and everything will be A-okay!

edited Jun 05 '14 at 20:27

Ed Rands

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answered May 28 '14 at 22:36

Kousha

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You only need to clear the cookies, not the history. – Mario Campa Jun 05 '14 at 13:57
I've got the same problem... It happens when multiple laravel sessions are opened in the same browser (It happened with firefox). I've removed `pma_*` and `laravel_session` cookies and everything went back to normal – IlGala Dec 22 '15 at 18:18

score 4 · Answer 2 · answered Jun 09 '14 at 05:51

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You need to change your cipher at app\config\app.php. Having same cipher name was causing that problem for me. I changed the cipher name uniquely & then it worked fine.

answered Jun 09 '14 at 05:51

user2432443

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score 2 · Answer 3 · answered Jul 16 '14 at 14:28

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This problem can also happen when you run more than one Laravel project/app with same Encryption Key. Just change key value in app/config/app.php with different value and you ready to go.

answered Jul 16 '14 at 14:28

Ifan Iqbal

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This should really be the accepted answer imo as it tackles the problem from the right angle - eliminating dual Laravel keys - rather than bypassing it. – Volzy Oct 12 '15 at 13:28

score 2 · Answer 4 · answered Feb 25 '15 at 09:51

Just elaborating on the answer from Ifan Iqbal. As he says this happens when running several Laravel installations with the same encryption key. Instead of clearing your cookies, simply create a unique key for each Laravel install you run (good practice by the way).

Go to your terminal and put:

php artisan key:generate

This will automatically set the encryption key in app/config/app.php and your error will go away.

Laravel : "mcrypt_decrypt(): The IV parameter must be as long as the blocksize"

4 Answers4