If a user has an issue with Microsoft Teams being unable to share a file in chat - take the following steps to resolve the issue. 


From Microsoft:     Clear Teams cache - Microsoft Teams | Microsoft Learn 

Classic Teams

  1. If Teams is still running, right-click the Teams icon on the taskbar, and then select Quit.

  2. Open the Run dialog box by pressing the Windows logo key  +R.

  3. In the Run dialog box, enter the following path, and then select OK:


    %appdata%\Microsoft\Teams

  4. Delete all files and folders in the directory.

  5. Restart Teams.

New Teams

Method 1: Reset the app

 Note

When you reset the Teams app, the app data will be deleted. This includes any personalization settings that you might have configured.

  1. Type settings in the search box, and then select the Settings app from the results.
  2. Select Apps > Installed apps, and then type Microsoft Teams in the search box.
  3. Locate the New Microsoft Teams app from the results, select the More options button (...) on the right, and then select Advanced options.
  4. In the Reset section, select Reset.
  5. Restart Teams.

Method 2: Delete the files

  1. If Teams is still running, right-click the Teams icon on the taskbar, and then select Quit.

  2. Open the Run dialog box by pressing the Windows logo key  +R.

  3. In the Run dialog box, enter the following path, and then select OK.

  4. %userprofile%\appdata\local\Packages\MSTeams_8wekyb3d8bbwe\LocalCache\Microsoft\MSTeams

  5. Delete all files and folders in the directory.

  6. Restart Teams.