If you organize an online meeting and you find yourself not being able to upload content and receive an error message, then...
- Verify that the file size of the content that you want to upload is not too large. PowerPoint presentations, Microsoft Word documents, multimedia, or snapshot slides are all converted during presentation, which expands/contracts the size of the original file
- Determine whether the Online Meeting quota was exceeded. By default, the meeting quota is set to 500 MB
- Determine whether more than the maximum number of files was uploaded to the Online Meeting. The total size of all files in a conference must not exceed 500 MB. Open the content bin and/or handouts to remove other files if the quota is exceeded
- Verify that the format of the file that you want to upload is in a format that can be uploaded. For more information about files that can be uploaded, see the following Microsoft webpage: Why Are My Users Unable to Use Communicator 2007 R2 to Transfer Files?
- Determine whether ports 443 or ports 50000-59999 are blocked by the Windows Internet Explorer HTTP proxy
- If you still cannot upload a document, collect Lync troubleshooting data by using The Microsoft Online Services Diagnostics and Logging (MOSDAL) support toolkit, and then escalate the issue to Office 365 Technical Support.
- You cannot upload or share content during a conference call in Lync Online - link