Fatal error: Call to undefined function hash() in wp-includes/sess

Try manually resetting your plugins. If that resolves the issue, reactivate each one individually until you find the cause.

If that does not resolve the issue, access your server via FTP or SFTP, navigate to /wp-content/themes/ and rename the directory of your currently active theme. This will force the default theme to activate and hopefully rule-out a theme-specific issue (theme functions can interfere like plugins).

Hi James.
I tried all those things. None of them worked. I’m still getting the same error message.
–j.

Ok, in that case, try downloading WordPress again and delete then replace your copies of everything except the wp-config.php file and the /wp-content/ directory with fresh copies from the download. This will effectively replace all of your core files without damaging your content and settings. Some uploaders tend to be unreliable when overwriting files, so don’t forget to delete the original files before replacing them.

Hi again, James.

I reloaded WP manually to no avail. I’m still getting the same error message:

Fatal error: Call to undefined function hash() in /home/web/ww3/wp-includes/session.php on line 64

When you uploaded the new files, did you specifically delete the old files, or did you overwrite them?

Also, now that you have uploaded the new files, try again with all plugins disabled (yes, all of them) and the Twenty Fourteen theme (specifically the Twenty Fourteen theme) enabled.

Hi James.

I did delete all the old files beforehand, and I did move the plugins to an “oldplugins” folder, as well as rename the active theme. Each time I got the same result, the error message you see above.

–j.

Are you using any sort of caching plugin, or do you see a “Clear/Purge Cache” button in your Dashboard or admin bar? If so, would you please try clearing the cache?

I cleared the cache and tried to log on with a different browser. Still getting the same message.

Not the cache in your browser, is there a cache in the WordPress Dashboard or admin bar?

If that’s what you meant, which version of PHP is your server running?

https://ww3.kellstrommaterials.com/phpinfo.php

Well, you’re ahead of the bunch. ??

I don’t have a way to test against 5.5.9 at the moment.

Is anything broken necessarily, or are you just seeing the error? If something is broken, could you describe what it is?

I can’t get into the dashboard. That’s pretty broken to me. However, the site appears fine as it’s served.

The sys admin is stingy with the PHP modules, so maybe he’s left something off that WP 4.0 needs to work.

This is lines 63 – 65 in /wp-includes/session.php:

final private function hash_token( $token ) {
return hash( ‘sha256’, $token );
}

I’m not a code guy, but isn’t this some kind of user verification function?

Hashing could certainly be disabled (though I really can’t think of any reason for anyone to do such a thing). Have you contacted your admin about this?

@macmanx, I suspect that the hash module is not loaded, in my phpinfo() output I get “hash support enabled”

I don’t see it here.
Does the hosting have the ability to enable hash ?
Is it a hosting issue. ?

Hi Ross.

I’ve got a message to the sys admin to enable hash. Thanks for your help.