Troubleshooting and FAQ
Questions
Are my files uploaded anywhere?
No. CompressX processes everything on your device. The home screen says so: everything runs on this device, with no uploads, no ads and no tracking.
Does CompressX change my original files?
No, it writes new files next to them. The one exception: if you turn off Keep original files in Settings, the image modules delete each original after processing it. See History and settings.
Can I make WEBP images?
No. CompressX can read WEBP images but cannot write them. Choose JPG or PNG instead.
Can I open HEIC photos from an iPhone?
No. HEIC files are not accepted. Convert them to JPG on the phone or with another tool first.
Can I make 7Z or RAR archives?
No. CompressX creates ZIP, TAR and TAR.GZ archives, and extracts ZIP, TAR, TAR.GZ, TGZ and GZ.
Why can I not compress video on Android?
Video, audio and PDF compression call FFmpeg and Ghostscript, which are not available on Android. On Android you can use the image modules, Images → PDF and Archive.
Where is the download?
There is no published release yet. Build CompressX from source as described in Install.
Troubleshooting
"FFmpeg was not found"
Cause: FFmpeg is not installed, or not on your system path.
Fix: Install it (sudo apt install ffmpeg on Ubuntu, winget install ffmpeg on Windows) and restart CompressX.
The PDF Compress button is greyed out
Cause: Ghostscript is not installed. The button also stays greyed out until you add a PDF.
Fix: Install Ghostscript (sudo apt install ghostscript qpdf on Ubuntu) and restart CompressX.
Merge is greyed out
Cause: You added fewer than two PDFs, or neither qpdf nor Ghostscript is installed.
Fix: Add at least two PDFs, and install qpdf or Ghostscript.
A file did not get smaller
Cause: The file was already well compressed. The row says already optimized, original kept.
Fix: Try a stronger setting: a lower Quality, a smaller Max dimension, or a preset such as Max compression. For PNG photos, convert to JPG.
"Skipped 1 unsupported file"
Cause: The file type is not one the module accepts. The accepted types are listed in the drop box.
Fix: Check the supported formats.
MP4 video fails but WEBM works
Cause: Your FFmpeg has no H.264 encoder (libx264). Fedora's ffmpeg-free is one example.
Fix: Install a full FFmpeg build, for example from RPM Fusion on Fedora.
"Could not read media duration for target-size mode."
Cause: FFmpeg could not find the length of the file, which Target size needs.
Fix: Set Target size to None and use the Quality slider or Bitrate instead.
A ZIP will not extract
Cause: The ZIP has a password and none (or a wrong one) was typed.
Fix: Type the password under Password (if encrypted) and try again.
Something else went wrong
Failed rows show the error under the file name. If you cannot solve it, report it on the CompressX issues page with the error text.