[wp-trac] [WordPress Trac] #36760: Intermittent empty returns from get_post_meta function after 4.5 upgrade

[WordPress Trac]

#36760: Intermittent empty returns from get_post_meta function after 4.5 upgrade
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 Reporter:  amberau            |      Owner:
     Type:  defect (bug)       |     Status:  new
 Priority:  normal             |  Milestone:  Awaiting Review
Component:  Posts, Post Types  |    Version:  4.5
 Severity:  normal             |   Keywords:
  Focuses:                     |
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 I've seen this reported several times, but the reporters failed to
 properly explain the issue and the tickets were closed.

 Since the 4.5 upgrade I am seeing intermittent issues in my custom plugin
 (which has worked for years and hasn't changed) where the get_post_meta
 function is used if the request is made via ajax or by calling a custom
 endpoint. Rolling back the 4.5 upgrade has resolved these issues.

 The same function called with exactly the same arguments will return the
 meta data value one minute and return an empty string the next (with
 single on). The data in the database is unchanged. Logging shows the post
 id and meta key are the same, only the return value is different. It
 always seems to work as part of a regular page request (not ajax, not
 custom endpoint).

 Sometimes the function works correctly for 24 hours, then fails several
 times. I can't identify any pattern but suspect the meta cache / session.
 I tried doing a meta cache update for the object before calling
 get_post_meta, but the problem still occurred.

 In Googling I've found several people reporting issues related to
 get_post_meta after the 4.5 update. Please take a look!

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Ticket URL: <https://core.trac.wordpress.org/ticket/36760>
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