How to trouble shoot "Photos keeps crashing or hanging" on iMac running High Sierra

This user tip has been reformatted and moved to: If Photos keeps crashing or Hanging - Trouble Shooting

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If photos is hanging or crashing there are many possible reasons. Systematic testing will help to narrow dozenth problem. Possible reasons are:Issues with the user library: Data error: it may be problem of corrupted or incompatible media files in your library, for example, if image files got corrupted during the download from the card or cable, if bad disk blocks damaged a file, or if you migrated an Aperture library or iPhoto Library, that contains media files that are incompatible with Photos.The location of the Library: a problem with the drive where the library is stored. A Photos library needs to be on a locally mounted drive with the file system format MacOS Extended (Journaled) or APFS: not a NAS or a synced cloud volume or you are risking library corruption and data loss: Is your Photos Library on a compatible drive as described here: Move your Photos library to save space on your Mac - Apple Support? The drive must not be used as a Time Machine volume.A damaged Photos Library: A Photos library may become damaged, if you try to share it between users on a drive, where the ownership cannot be ignored, if you run dangerous cleaning software to remove duplicates, restore it incorrectly from a Time Machine backup, also repeated crashes can damage the library.An incompatible library: Photos cannot use a Photos Library, that has been opened by a new version of Photos.Problems with your User Account: corrupted preferences files or caches in your user library, incorrect permissions and access control lists in your home folder can prevent Photos from accessing or saving information in your user librarySystem wide issues:Lack of storage: Photos cannot work properly, if you do not have enough free storage on your system drive, the drive with the library, or in iCloud, if you are using iCloud Photo Library.Corrupted system cachesAn incomplete installation of MacOS X.Incompatible, older applications or other software like fonts or color profiles. Older allocations may have installed system extensions that can destabilize your system.Hardware problems: Typical hardware problems are a failing drive, not enough memory or a problem with the installed memory, a problem with the graphics card.

With so many possible reasons for crashes or hanging, it can be a bit daunting to track down the reason, why Photos may be crashing or hanging. The first thing to do, is to check your storage situation.Do you have enough free storage on your system drive and the drive with the library?If iCloud Photo library is enabled, do you have enough free cloud storage? Are you connected to the internet using Wi-fi?Did you recently import new media files into the library - new photos or videos?

• Try to narrow down the problem with a few tests:Try to find out, if the crashes only happen for your current Photos Library.
• You do that by creating a new library and importing a few photos for testing.

See: Create additional photo libraries in Photos on Mac - Apple SupportIf the crashes happen also on a new library, check if the problem is system wide or only happens in your main account. You can do that by testing in a different user account. See this document: Isolating an issue by using another user accountIf the problem is system wide, test if you installed incompatible system extensions by booting into Save Mode. This will clear caches and temporarily disable this party system extensions, so you will be testing with a clean system: Mac OS X: Starting up in Safe Mode

Depending on your test results, pick one of the fixes described here: Get help with the Photos app on your Mac - Apple Support

This user tip was generated from the following discussion: Photos keeps crashing on iMac running High Sierrra