Unknown error when reordering structure

[Emkaytoo]

Description

User with Admin-level permissions is unable to reorder structures by dragging and dropping. When attempting to reorder entries, the entry appears to move, but an alert appears saying An unknown error occurred. Upon refreshing the entries page, the entry has reverted back to it's original position.

Steps to reproduce

1. Create a multi-level structure, and create two levels of content
2. Reorder the content via drag-and-drop in the Structure's entry section
3. The error will appear

Additional info

This issue happens consistently and predictably with multi-level structures. On single-level structures, it happens intermittently. Sometimes user can reorder (new position saved), sometimes the error appears.

• Craft version: Pro 3.0.9
• PHP version: 7.1.17
• Database driver & version: MySQL 5.7.12
• Plugins & versions:

Plugin	Version
Amazon S3	1.0.8
Architect	2.2.8
Blockonomicon	1.1.1
Blockonomicon Super Table Adapter	1.0.0
Cookies	1.1.9
CP Field Inspect	1.0.4
Eager Beaver	1.0.3
Element API	2.5.2
Element Map	1.0.2
Entry Instructions	1.0.0
Expanded Singles	1.0.3
Freeform Lite	2.0.3
Guide	1.2.1
ImageOptimize	1.4.33
Instant Analytics	1.0.6
Json Client	1.0.1
Minify	1.2.8
Preparse Field	1.0.0
Redactor	2.1.0
SEOmatic	3.0.18
Smart Map	3.1.0
Snitch	2.0.1
SuperSort	3.0.1
Super Table	2.0.7
Template Select	2.0.0
Twig Profiler	1.0.0
Typed link field	1.0.8
Typogrify	1.1.10

[Emkaytoo]

Update: After reading #2772, I realized this was happening on our stage environment. I tried testing on dev and was able to reorder an entry successfully. However, I was unable to move the repositioned entry back to it's original spot.

Conclusion: this is happening consistently on stage and intermittently on dev.

[Emkaytoo]

Also, I'm not sure how much this influences the priority, but we have a site launching in 2 weeks, and we're in a Content QA phase. Do with that information what you will.

[brandonkelly]

@Emkaytoo Can you email a database backup and your composer.json & composer.lock files over to [email protected] ?

[Emkaytoo]

This was a result of a load balancer issue. The Craft team recommended using the Yii 2 Redis extension for keeping session data synced.

[brandonkelly]

Glad moving to Redis got this sorted!