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Captcha broken image

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What to do if you have a technical problem with OJS:

1. Search the forum. You can do this from the Advanced Search Page or from our Google Custom Search, which will search the entire PKP site. If you are encountering an error, we especially recommend searching the forum for said error.

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Captcha broken image

Postby netdiver » Wed Feb 05, 2014 2:52 am

Dear all,
I've found a strange behaviour in our OJS (and OCS) installation related to captcha.

After successfully enabling captcha, after some days we found that image was not displayed (broken image icon from the browser).
The (strange) solution I have found to fix the problem was to restart Apache web server.

There are no 404 or other messages in the logs related to this problem.

I have no idea of why it happens, but I found out that if I change the format of the captcha image from PNG to JPEG in lib/pkp/classes/captcha/CaptchaManager.inc.php
in lines 70 and 115 I obtain a captcha without restarting Apache server.

Does anyone knows why it happens?
Thanks in advance
Regards from Lorenzo
netdiver
 
Posts: 10
Joined: Wed Dec 21, 2011 4:02 am

Re: Captcha broken image

Postby asmecher » Wed Feb 05, 2014 10:15 am

Hi netdiver,

Most likely this is due to the level of support for PNG images in the libgd library that OJS uses to generate images, i.e. perhaps your PHP was compiled without libpng support.

Regards,
Alec Smecher
Public Knowledge Project Team
asmecher
 
Posts: 9210
Joined: Wed Aug 10, 2005 12:56 pm

Re: Captcha broken image

Postby netdiver » Thu Feb 06, 2014 5:02 am

Thanks Alec for reply.
I am using Debian 7 php5 package, and the strange thing is that if I have a freshly restarted apache, the PNGs are correctly generated, after some days of uptime, the PNGs are broken.
netdiver
 
Posts: 10
Joined: Wed Dec 21, 2011 4:02 am

Re: Captcha broken image

Postby asmecher » Fri Feb 07, 2014 1:09 pm

Hi netdiver,

Hmm, strange -- unfortunately it sounds to me like a platform issue (server / PHP / libgd), as there's nothing in OJS that would explain intermittent function like you describe.

Regards,
Alec Smecher
Public Knowledge Project Team
asmecher
 
Posts: 9210
Joined: Wed Aug 10, 2005 12:56 pm


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