AE 2026 (26.5): Project items created by an effect plugin during SEQUENCE_SETUP desync the render thread; new solids and footage stop rendering ("need a full sync: unimplemented")
If an effect plugin creates a project item while it's being applied, After Effects 2026 stops rendering new solids and footage in that project until the project is closed and reopened. Saving the project doesn't help, but File > Close Project followed by reopening it does, with no After Effects restart needed.
Specifically, this means calling AEGP_ExecuteScript with app.project.items.addComp(...) from PF_Cmd_SEQUENCE_SETUP.
The new layers show up in the timeline with a normal selection box, but nothing draws. Removing the effect and purging caches don't fix it either. The project file itself is not damaged.
The AE log shows the render thread's copy of the project falling out of sync and never recovering:
<DBSync> ProcessFromRenderThread ZANZIBAR-1: synchronization integrity correction: database timestamp mismatch: proj=64, sanity=88
<BEE WorkQueue General Render Thread> <assert> Assertion Failed
message: "Render_ExecuteCommand: serialization failed; need a full sync: unimplemented"
sourceFile: "...\BEE\workqueue\BEE_ThreadedRenderUpdateQueue.cpp" sourceLine: 1587
The same plugin works fine in After Effects 2025. It's still broken in the 27.1 beta.
Ready-to-build minimal repro: https://github.com/ribvault/ae2026-sequence-setup-sync-repro. It contains a README and a patch for the SDK's own Skeleton sample; no Adobe SDK files are included.
Steps to reproduce
Apply the patch from https://github.com/ribvault/ae2026-sequence-setup-sync-repro to the SDK's own Skeleton sample, or add this one case to EffectMain by hand:
case PF_Cmd_SEQUENCE_SETUP:
{
AEGP_SuiteHandler suites(in_data->pica_basicP);
static AEGP_PluginID s_pluginID = 0;
if (s_pluginID == 0)
suites.UtilitySuite6()->AEGP_RegisterWithAEGP(NULL, "AE2026 Sync Repro", &s_pluginID);
AEGP_MemHandle resultH = NULL, errorH = NULL;
suites.UtilitySuite6()->AEGP_ExecuteScript(
s_pluginID,
"app.project.items.addComp('SyncRepro Comp', 100, 100, 1, 1, 30);",
FALSE, &resultH, &errorH);
if (resultH) suites.MemorySuite1()->AEGP_FreeMemHandle(resultH);
if (errorH) suites.MemorySuite1()->AEGP_FreeMemHandle(errorH);
break;
}
The effect name and match name are also changed, to avoid clashing with the stock Skeleton. Then:
- Build the modified Skeleton and launch After Effects 2026.
- New project. Import any footage, or create a solid, and make a comp from it.
- Add a text layer and apply the repro effect to it. A comp named "SyncRepro Comp" appears in the Project panel, as expected.
- Add a new solid (Layer > New > Solid), or import another piece of footage and drop it into the comp.
Expected result
The new solid or footage renders, as it does in After Effects 2025.
Actual result
- The new solid or footage appears in the timeline but never renders.
- The DBSync / "need a full sync: unimplemented" messages above appear in the log, starting during step 3.
- Every new project item added to that project from then on is affected, until the project is closed and reopened (File > Close Project, then reopen). Saving alone doesn't help.
Additional findings
| Where the plugin creates the project item | Result in AE 26.5 |
|---|---|
PF_Cmd_SEQUENCE_SETUP via AEGP_ExecuteScript | ❌ desync |
PF_Cmd_SEQUENCE_SETUP via AEGP_CreateComp | ❌ desync |
PF_Cmd_UPDATE_PARAMS_UI via AEGP_ExecuteScript | ❌ desync (new text layers still render; new solids and footage don't) |
PF_Cmd_USER_CHANGED_PARAM (button click, or a param changed by a scheduled script) | ✅ fine |
| AEGP idle hook | ✅ fine |
Likely cause: in AE 2025, the render thread's copy was rebuilt from scratch when an incremental update failed, and AE 2026 no longer does that ("need a full sync: unimplemented").
Workaround: in SEQUENCE_SETUP, call app.scheduleTask to change a hidden supervised parameter just after the effect is applied, and create the item in USER_CHANGED_PARAM. It works, but it adds an extra undo step. Open question: are project changes during SEQUENCE_SETUP now unsupported, or is this a regression?
Adobe After Effects version
26.5 (Windows). Also present in the 27.1 beta. Not present in 2025.
Operating system
Windows 11 Enterprise 25H2 (build 26200)
GPU driver version
NVIDIA RTX A4000, driver 596.71. Also seen on a second machine with an NVIDIA RTX 4000 Ada. Not GPU-related: the plugin's own GPU path reported 0 errors.
Video format
Not related. It happens with an .mp4 or with plain solids.
Comparative information
- Affects any project the effect has been applied to, until that project is closed and reopened. The saved project file is not damaged.
- Reproduces in brand-new projects.
- Started with After Effects 2026. Works in 2025.
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