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I updated my CiviCRM version to 4.7.27 yesterday and got a Performance warning on my system status page that there are some Missing indices. Clicking the 'Update Indices' button doesn't fix the problem and gives an error:

Operation failed: Update Indices
DB Error: unknown error
Debug information:
DROP INDEX UI_case_contact_id ON civicrm_case_contact [nativecode=1025 ** Error on rename of './rmcivicrm/#sql-6a4_f3186b' to './rmcivicrm/civicrm_case_contact' (errno: 150)]

I'm using Civicrm in Wordpress 4.9. Anyone please enlighten me on how to solve this error?

marked as duplicate by Demerit, William Mortada, Christia, Jon G - Megaphone Tech, petednz - fuzion Dec 11 '17 at 22:36

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