Error serializing chat session for storage. The session will be lost if the window is closed.

[jordan-stoner]

• VS Code Version: 1.115.0
• OS Version: Tahoe 26.3.1

Steps to Reproduce:

1. Open VS Code
2. Open an existing Github Copilot chat with a very long history the following error appears:

Error serializing chat session for storage. The session will be lost if the window is closed. Please report this issue to the VS Code team:

RangeError: Invalid string length
at JSON.stringify ()
at TQ.write (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:2881:644)
at coe.writeSession (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:2883:11717)
at vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:2883:8678
at Array.map ()
at vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:2883:8666
at vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:406:73795