Can ID 2024 19.5 no longer open older ID documents(before 2021 year)?

Sounds like you’re leaving something out. You need to tell us the exact version they were created in and exactly what the problem is. I have files that are more than 25 years old that still open just fine in current versions of InDesign.

Short answer: no, Adobe InDesign 2024 (v19.5) should open INDD files created before 2021. I’m not aware of a hard compatibility cutoff like that. What you’re seeing is more likely a performance or file-conversion issue rather than a version limitation.

Older INDD files normally open forward without issue. InDesign is designed to be backward-compatible. A pre-2021 file should open directly in 2024 without needing IDML at all. If it’s slow or hanging, it usually points to something else, corrupt elements, legacy fonts, outdated plugins, or very heavy assets.

The behaviour you’re describing, IDML taking a long time to open, is actually expected. IDML is a full rebuild of the document, not just a simple conversion. When you open an IDML, InDesign reconstructs everything from scratch, which can be significantly slower, especially for complex or older documents.

On the 2026 vs 2024 point, newer versions (like 2026) sometimes handle legacy files better because Adobe updates the internal conversion engine. That’s why it may open there first, but feel “sluggish” overall.

There isn’t a true “one-click batch downgrade to 2024” built into InDesign, but there are workable approaches:

• InDesign scripting (ExtendScript / JavaScript) can batch process files:
  • Open INDD
  • Export to IDML
  • Save/close
    This can be run on an entire folder.

Typical workflow in practice:

1. Open batch in 2026
2. Script exports all to IDML
3. Open IDMLs in 2024 (first open will still be slow)
4. Save as InDesign file

If performance is the main pain, try this before scripting:

• Clear font cache / check missing fonts
• Disable third-party plugins
• Package the document and relink assets
• Try opening with “ignore local settings” (Shift+Ctrl/Cmd while opening)

​@dublove specify or share the file you say “from before 2021” we need to make sure what version it was last saved in. Also, when it does not open what error do you get? Does it happen with some file or all the files?