Month view causing php memory limit error with WP Super Cache

[liblogger]

Hi there – since upgrading to ECPro 4.2.2 (and subsequently 4.2.3), the month view of the events calendar has being giving us a fatal error. On the page we see:

Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0

While the error log gives us:

[25-Jul-2016 11:49:59 Europe/London] PHP Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 263197 bytes) in /[…]/wp-content/plugins/wp-super-cache/wp-cache-phase2.php on line 411
[25-Jul-2016 11:49:59 Europe/London] PHP Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0

It does seem to be a conflict with WP Super Cache (i.e. there’s no issue when the caching is turned off), and it’s also definitely Events Calendar Pro that’s having problems, as there’s no issue when ECPro is turned off. The caching plugin hasn’t been changed recently – there was no conflict before we did this last update (we may have missed a couple of ECPro updates, however).

The error occurs for both looged in users (who aren’t served cached pages), and anonymous users. Our test site didn’t have any issues, but it also doesn’t have many events.

We’re on shared hosting, so we’re not able to increase the PHP memory limit. I’d be grateful for any input about ways to deal with this problem (I’m aware that it may be an issue with the caching plugin, but as it’s only occured with the recent update to ECPro, I want to raise it here as well).

NB: I have turned off the Month view on our website – let me know if you want to see the error message in situ.

[Cliff]

Hi. Sorry you’re experiencing this, and thanks for all the details.

Could you please make sure all your Modern Tribe plugins (and WordPress core) are at their latest versions?

• Downloads / Version Numbers
• TEC Automatic Updates
• or TEC Manual Updates
• WordPress core updates

Once you verify you’re on the latest versions, please test to see if the issue is still happening for you.

If it is, please follow our Testing for Conflicts Guide (basically switch to TwentySixteen theme and deactivate all plugins and custom code other than Modern Tribe plugins) and see if that helps narrow down the cause of this.

If it doesn’t, please enable WP_DEBUG and WP_DEBUG_LOG and share any PHP errors you see while changing tickets quantity, navigating your site’s home page, events page, single-event pages, and any other of your site’s pages relevant to this ticket.

Then, please share your System Information (while in Testing for Conflicts mode).

You might also see if you can spot any console errors at your site. (If needed, you may reference our KB article Using Google Chrome Developer Tools.)

Let us know what you find out.

Thanks.

[Cliff]

Another idea:

It’s hard to tell if this is your issue or not, but please do strongly consider trying out this temporary plugin fix for runaway recurring events (a bug introduced in version 4.2.2 and fixed within a few days via version 4.2.2.1). If you do try the fix, please do follow the instructions carefully and allow time (maybe 1-2 days) for it to work its fix into all your events.

Please let me know how it goes for you or if you didn’t try it.

[liblogger]

Hi – thanks for the prompt response.

As far as I’m aware, the system info was copied into the supplied box on my initial post – if it was lost while I was switching between tabs to double check all the errors, I apologise for not clarifying. We are using the current version of WP, your plugins (the calendar, the ticketing plugin and the pro version of both), and WP Super Cache, as well as the other plugins we use. I did check for other conflicts with plugins; I didn’t switch to the default theme as it’s a production site – as indicated, I installed the updates after running them on a test site, where this error was not occurring. I’ve tried reproducing the error on the test site by importing all the events, but without any luck.

I will have to wait for a quieter period of site usage before switching the theme, and will let you know if I see any change.

Digging around again in the events calendar settings, I can get the month view to display sporadically for anonymous users if I reduce the number of events displaying per day, but unfortunately it still fails for logged in users (we have people logging in to buy tickets). And if I skip ahead to a month with relatively few events, it works, but that’s only going to last until the next lot of events are added…

I’ve turned on the debugging and let it run while adding an event as well as navigating the site – I’m not able to upload the file, so do let me know how best to share it with you.

(I installed the recurring event bug-fix plugin, as there was one recurring event with a couple of duplicate entries for events that were edited out of the series – it subsequently created a new instance of the recurring event on a date that doesn’t meet any of the original criteria, but doesn’t seem to have removed any of the duplicates – I’ve turned it off.)

[Cliff]

We did receive the initial system information, as you stated. However, you stated you weren’t able to go through our Testing for Conflicts steps at this time. When you do, if you still have issues, please then share your system information again (while in Testing for Conflicts mode).

Regarding WP Super Cache:

A couple of us tried WP Super Cache (turn it on in easy mode) and didn’t experience any issues.

Could you tell me which WP Super Cache settings you have that differ from the defaults (annotated screenshots or other methods)?

[liblogger]

I don’t think we have any settings different from default/recommended settings – the only one might be ‘Don’t cache pages for known users’ which is recommended but not selected by default (I think!), but I didn’t see any change when switching that off.

However, the month view is currently working, and it does look as if it was related to a problem with recurring events: I thought your bug-fix plugin had just created a single additional instance of the event on the day it was activated, but it had actually created instances for every day of the period from the first instance to that date. I’d unpublished the first instance, and the upcoming duplicate entries, but hadn’t noticed the ‘past’ instances – when I unpublished those, the month view started working again. (I’m holding off on saying it’s working until we turn over to next month, as we have more events next month, so if it’s simply a question of scale (rather than generating random recurring events), it may still fail).

[Cliff]

Thanks for the update. I’m glad to hear we’re at least moving in the right direction.

I’ll wait to hear back from you on this topic…

Please note that threads get Closed automatically after a couple weeks of inactivity. If it does get Closed, please open a new thread, adding your current problem description and also linking back to this thread.

Thank you!

[Support Droid]

Hey there! This thread has been pretty quiet for the last three weeks, so we’re going to go ahead and close it to avoid confusion with other topics. If you’re still looking for help with this, please do open a new thread, reference this one and we’d be more than happy to continue the conversation over there.

Thanks so much!
The Events Calendar Support Team

[Author]

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