Title: Undefined array key
Last modified: March 1, 2023

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# Undefined array key

 *  Resolved [montgoc1](https://wordpress.org/support/users/montgoc1/)
 * (@montgoc1)
 * [3 years, 2 months ago](https://wordpress.org/support/topic/undefined-array-key-20/)
 * When I upgrade our PHP version to 8.1, I get multiple warnings related to the
   array key being undefined. I assume it’s coming from the Bookshelves plugin based
   on the warning.
 * Following are two examples appear above the header:
    1. Warning: Undefined array key “lbs_cat_URL” in /…/…/…/…/wp-content/plugins/library-
       bookshelves/functions.php on line 91
 *  1. Warning: Undefined array key “lbs_cat_CDN_URL” in /…/…/…/…/wp-content/plugins/
       library-bookshelves/functions.php on line 107
 * For the time being I have downgraded PHP to correct the issue. I also assume 
   it’s specific to our site, since I can’t find any other posts about it. I am 
   just hoping someone else has some insight.
 * Any assistance is appreciated.
 * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fundefined-array-key-20%2F%3Foutput_format%3Dmd&locale=en_US)
   to see the link]_

Viewing 2 replies - 1 through 2 (of 2 total)

 *  Plugin Author [photonicgnostic](https://wordpress.org/support/users/photonicgnostic/)
 * (@photonicgnostic)
 * [3 years, 2 months ago](https://wordpress.org/support/topic/undefined-array-key-20/#post-16519432)
 * Resaving your plugin settings will get rid of these errors. This is a bug that
   will be fixed in the next release.
 *  Thread Starter [montgoc1](https://wordpress.org/support/users/montgoc1/)
 * (@montgoc1)
 * [3 years, 2 months ago](https://wordpress.org/support/topic/undefined-array-key-20/#post-16521612)
 * Brilliant! Thank you; it worked.

Viewing 2 replies - 1 through 2 (of 2 total)

The topic ‘Undefined array key’ is closed to new replies.

 * ![](https://ps.w.org/library-bookshelves/assets/icon-256x256.png?rev=1720814)
 * [Library Bookshelves](https://wordpress.org/plugins/library-bookshelves/)
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## Tags

 * [array key](https://wordpress.org/support/topic-tag/array-key/)

 * 2 replies
 * 2 participants
 * Last reply from: [montgoc1](https://wordpress.org/support/users/montgoc1/)
 * Last activity: [3 years, 2 months ago](https://wordpress.org/support/topic/undefined-array-key-20/#post-16521612)
 * Status: resolved