MemberPress Sites Are Crashing Because of an Add-on Abandoned Years Ago (Here’s the Fix)

If your WordPress site just went down with a “Your Site is Experiencing a Technical Issue” email, and the error details point at MemberPress with a message like this, you’re in the right place:

An error of type E_ERROR was caused in line 19 of the file
.../wp-content/plugins/memberpress/app/lib/MeprAddonUpdates.php.
Error message: Trait "MemberPress\GroundLevel\Container\Concerns\InjectsDependencies" not found

We just diagnosed and fixed this exact crash on a client’s membership site, and the cause surprised us enough that we’re writing it up. The short version: MemberPress is not actually the broken plugin. The culprit is an old MemberPress add-on, the Constant Contact integration, that was quietly abandoned years ago and finally became fatal when MemberPress updated its internal code.

Why WordPress blames the wrong plugin

The fatal error email names “MemberPress” (or “MemberPress Basic (Legacy)”) as the current plugin, because the crash technically happens inside a MemberPress file. So the natural first move, deactivating or reinstalling MemberPress, doesn’t fix anything. The real trigger is the MemberPress Constant Contact add-on. It reaches directly into MemberPress’s folder and force-loads one of MemberPress’s internal files (the license and update checker, a file called MeprAddonUpdates.php) before MemberPress itself has loaded. When MemberPress rewrote that file’s internals in their 1.12 release line, the old add-on started loading a file whose dependencies don’t exist yet, and PHP dies on the spot.

How long was this thing abandoned? We checked.

We dug through the add-on’s code and the public record, and the timeline is remarkable:

• 2015: The plugin’s copyright header ends at 2015, and it is built on Constant Contact’s old v2 API from that era.
• Late 2019: The last functional code change we could identify. Version 1.1.4’s only real addition is a compatibility notice referencing MemberPress 1.7.3, which shipped December 10, 2019.
• June 2023: The last touch of any kind, a regenerated translation file. No code changes.
• October 2024: The Wayback Machine shows MemberPress’s documentation still describing the add-on as “included with your purchase of the Basic, Plus, or Pro” plan, installable right from the WordPress dashboard.
• Sometime after that: The documentation page was quietly replaced with a generic page recommending third-party integration plugins instead. We could not find any public announcement that the add-on was discontinued.
• March 2025: MemberPress 1.12.0 ships, beginning the internal rewrite that the old add-on cannot survive.
• August 2026: MemberPress 1.12.17 rolls out, and sites still running the add-on start going down with the fatal error above.

Put plainly: this integration was advertised as an included feature for roughly five years after anyone stopped maintaining it, then delisted without announcement. Since it was still being promoted as recently as late 2024, there are very likely many sites out there with it installed, all of them a MemberPress update away from this crash, if it hasn’t hit them already.

How to get your site back up right now

1. Use the “recovery mode” link in the email WordPress sent you (or connect via FTP/your host’s file manager).
2. If using FTP, rename the folder wp-content/plugins/memberpress-constantcontact to anything else (for example, add -off to the end). WordPress will deactivate it and your site will come back immediately.
3. If using recovery mode, deactivate the “MemberPress Constant Contact” plugin from the Plugins screen, then exit recovery mode.

Do not deactivate MemberPress itself. It isn’t the problem, and deactivating it takes your membership site features down with it.

Want to keep the Constant Contact integration working? We patched it.

Deactivating the add-on stops the crash, but it also stops new members from being synced to your Constant Contact lists. Since the vendor no longer offers or supports this add-on, we patched it ourselves. The broken portion was the plugin’s license and update checker, which is dead weight anyway (there will never be another official update to check for). We removed it, left the actual Constant Contact syncing untouched, and bumped the version to 1.1.5.

Download the patched MemberPress Constant Contact 1.1.5 (unofficial community patch)

To install it: go to Plugins > Add New > Upload Plugin, upload the zip, and when WordPress tells you the plugin is already installed, click “Replace current with uploaded.” That’s it. Your settings, API key, and list assignments are stored in the database and are not affected.

A few important notes about this download:

• This is an unofficial patch by Sharp Guys Web Design. We are not affiliated with Caseproof, MemberPress, or Constant Contact, and those names are trademarks of their respective owners. The plugin is distributed under the GPL, the same license all WordPress plugins carry, with the original copyright notices intact.
• It is provided as-is, without warranty. Back up your site before installing anything, always.
• This patch fixes the crash. It does not modernize the integration. The add-on still talks to Constant Contact through their older v2 API, which Constant Contact has been phasing out in favor of v3. When Constant Contact finally shuts the old system off, the syncing will stop working no matter what, and at that point the integration needs to be rebuilt on their current platform (or replaced with a supported alternative). Nobody can patch around that day, so treat this fix as breathing room, not a forever solution.

The bigger lesson

Premium plugin add-ons don’t always die loudly. This one kept “working” for years after its last real update, kept being promoted, and only revealed it was abandoned when the platform underneath it moved. If your site depends on integrations between paid plugins, it’s worth having someone periodically verify they’re still supported, before an automatic update turns a quiet abandonment into a 8am “your site is down” email.

If your membership site is down with this error and you’d rather have someone else handle it, get in touch. We’ve already been through this one end to end.